STILLWATER MINING COMPANY

Exhibit 1.1

EXECUTION COPY

$345,000,000

STILLWATER MINING COMPANY

1.75% Convertible Senior Notes due 2032

UNDERWRITING AGREEMENT

October 11, 2012

CREDIT SUISSE SECURITIES (USA) LLC

▇▇▇▇▇ FARGO SECURITIES, LLC

As Representative of the Several Underwriters,

c/o Credit Suisse Securities (USA) LLC,

Eleven Madison Avenue,

New York, N.Y. 10010-3629

Dear Sirs:

1. Introductory. Stillwater Mining Company, a Delaware corporation (the “Company”), agrees with the several Underwriters named in Schedule A hereto (“Underwriters”) for whom you are acting as representative (“Representative”) to issue and sell to the several Underwriters $345,000,000 principal amount (“Firm Securities”) of its 1.75% Convertible Senior Notes due 2032 (“Securities”) and also agrees to issue and sell to the Underwriters, at the option of the Underwriters, an aggregate of not more than $51,750,000 additional principal amount (“Optional Securities”) of its Securities as set forth below, all to be issued under an indenture, dated as of November 29, 2010 (the “Base Indenture”) between the Company and Law Debenture Company, as Trustee, as supplemented by a supplemental indenture, dated as of the First Closing Date (the “Supplemental Indenture” and, together with the Base Indenture, the “Indenture”), between the Company the Trustee. The Firm Securities and the Optional Securities are herein collectively called the “Offered Securities”. References to “Representative” herein shall refer to both Credit Suisse Securities (USA) LLC and ▇▇▇▇▇ Fargo Securities, LLC.

2. Representations and Warranties of the Company. (a) The Company represents and warrants to, and agrees with, the several Underwriters that:

(i) Filing and Effectiveness of Registration Statement; Certain Defined Terms. The Company has filed with the Commission a registration statement on Form S-3 (No. 333-170851), including a related prospectus or prospectuses, covering the registration of the Offered Securities under the Act, which has become effective. “Registration Statement” at any particular time means such registration statement in the form then filed with the Commission, including any amendment thereto, any document incorporated by reference therein and all 430B Information and all 430C Information with respect to such registration statement, that in any case has not been superseded or modified. “Registration Statement” without reference to a time means the Registration Statement as of the Effective Time. For purposes of this definition, 430B Information shall be considered to be included in the Registration Statement as of the time specified in Rule 430B.

For purposes of this Agreement:

“430B Information” means information included in a prospectus then deemed to be a part of the Registration Statement pursuant to Rule 430B(e) or retroactively deemed to be a part of the Registration Statement pursuant to Rule 430B(f).

“430C Information” means information included in a prospectus then deemed to be a part of the Registration Statement pursuant to Rule 430C.

“Act” means the Securities Act of 1933, as amended.

“Agreement” means this underwriting agreement.

“Applicable Time” means 8:45 pm (Eastern time) on the date of this Agreement.

“Closing Date” has the meaning defined in Section 3(c) hereof.

“Commission” means the Securities and Exchange Commission.

“Effective Time” of the Registration Statement relating to the Offered Securities means the time of the first contract of sale for the Offered Securities.

“Exchange Act” means the Securities Exchange Act of 1934, as amended.

“Final Prospectus” means the Statutory Prospectus that discloses the public offering price, other 430B Information and other final terms of the Offered Securities and otherwise satisfies Section 10(a) of the Act.

“General Use Issuer Free Writing Prospectus” means any Issuer Free Writing Prospectus that is intended for general distribution to prospective investors, as evidenced by its being so specified in Schedule B to this Agreement.

“Issuer Free Writing Prospectus” means any “issuer free writing prospectus,” as defined in Rule 433, relating to the Offered Securities in the form filed or required to be filed with the Commission or, if not required to be filed, in the form retained in the Company’s records pursuant to Rule 433(g).

“Limited Use Issuer Free Writing Prospectus” means any Issuer Free Writing Prospectus that is not a General Use Issuer Free Writing Prospectus.

“Rules and Regulations” means the rules and regulations of the Commission.

“Securities Laws” means, collectively, the ▇▇▇▇▇▇▇▇-▇▇▇▇▇ Act of 2002 (“▇▇▇▇▇▇▇▇-▇▇▇▇▇”), the Act, the Exchange Act, the Trust Indenture Act, the Rules and Regulations, the auditing principles, rules, standards and practices applicable to auditors of “issuers” (as defined in ▇▇▇▇▇▇▇▇-▇▇▇▇▇) promulgated or approved by the Public Company Accounting Oversight Board and, as applicable, the rules of the New York Stock Exchange (“Exchange Rules”).

“Statutory Prospectus” with reference to any particular time means the prospectus relating to the Offered Securities that is included in the Registration Statement immediately prior to that time, including all 430B Information and all 430C Information with respect to the Registration Statement. For purposes of the foregoing definition, 430B Information shall be considered to be included in the Statutory Prospectus only as of the actual time that form of prospectus (including a prospectus supplement) is filed with the Commission pursuant to Rule 424(b) and not retroactively.

“Trust Indenture Act” means the Trust Indenture Act of 1939, as amended.

“Underlying Shares” means shares of common stock, $0.01 par value per share (the “Common Stock”), of the Company into which the Securities are convertible (subject to the Company’s right to pay cash, in whole or in part, upon conversion of the Offered Securities in satisfaction of the Company’s conversion obligation).

Unless otherwise specified, a reference to a “Rule” is to the indicated rule under the Act.

(ii) Compliance with Securities Act Requirements. (A) (1) At the time the Registration Statement initially became effective, (2) at the time of each amendment thereto for the purposes of complying with Section 10(a)(3) of the Act (whether by post effective amendment, incorporated report filed pursuant to Section 13 or 15(d) of the Exchange Act or form of prospectus), (3) at the Effective Time relating to the Offered Securities and (4) on the Closing Date, the Registration Statement conformed and will conform in all material respects to the requirements of the Act, the Trust Indenture Act and the Rules and Regulations and did not and will not include any untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary to make the statements therein not misleading and (B) (1) on its date, (2) at the time of filing the Final Prospectus pursuant to Rule 424(b) and (3) on the Closing Date, the Final Prospectus will conform in all material respects to the requirements of the Act, the Trust Indenture Act and the Rules and Regulations and will not include any untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary to make the statements therein not misleading. The preceding sentence does not apply to statements in or omissions from any such document based upon written information furnished to the Company by any Underwriter through the Representative specifically for use therein, it being understood and agreed that the only such information furnished by any Underwriter is that described as such in Section 8(b) hereof.

(iii) Automatic Shelf Registration Statement. (A) Well-Known Seasoned Issuer Status. (1) At the time of initial filing of the Registration Statement, (2) at the time of the most recent amendment thereto for the purposes of complying with Section 10(a)(3) of the Act (whether such amendment was by post-effective amendment, incorporated report filed pursuant to Section 13 or 15(d) of the Exchange Act or form of prospectus) and (3) at the time the Company or any person acting on its behalf (within the meaning, for this clause only, of Rule 163(c)) made any offer relating to the Offered Securities in reliance on the exemption of Rule 163, the Company was a “well known seasoned issuer” as defined in Rule 405, including not having been an “ineligible issuer” as defined in Rule 405.

(B) Effectiveness of Automatic Shelf Registration Statement. The Registration Statement is an “automatic shelf registration statement,” as defined in Rule 405, that initially became effective within three years of the date of this Agreement. If immediately prior to the Renewal Deadline (as hereinafter defined), any of the Offered Securities remain unsold by the Underwriters, the Company will prior to the Renewal Deadline file, if it has not already done so and is eligible to do so, a new automatic shelf registration statement relating to the Offered Securities, in a form satisfactory to the Lead Underwriter (as defined in Section 3). If the Company is no longer eligible to file an automatic shelf registration statement, the Company will prior to the Renewal Deadline, if it has not already done so, file a new shelf registration statement relating to the Offered Securities, in a form satisfactory to the Representative, and will use its best efforts to cause such registration statement to be declared effective within 180 days after the Renewal Deadline. The Company will take all other action necessary or appropriate to permit the public offering and sale of the Offered Securities to continue as contemplated in the expired registration statement relating to the Offered Securities. References herein to the Registration Statement shall include such new automatic shelf registration statement or such new shelf registration statement, as the case may be. “Renewal Deadline” means the third anniversary of the initial effective time of the Registration Statement.

(C) Eligibility to Use Automatic Shelf Registration Form. The Company has not received from the Commission any notice pursuant to Rule 401(g)(2) objecting to use of the automatic shelf registration statement form. If at any time when Offered Securities remain unsold by the Underwriters the Company receives from the Commission a notice pursuant to Rule 401(g)(2) or otherwise ceases to be eligible to use the automatic shelf registration statement form, the Company will (1) promptly notify the Representative, (2) promptly file a new registration statement or post-effective amendment on the proper form relating to the Offered Securities, in a form satisfactory to the Representative, (3) use its reasonable best efforts to cause such registration statement or post-effective amendment to be declared effective as soon as reasonably practicable and (4) promptly notify the Representative of such effectiveness. The Company will take all other action necessary or appropriate to permit the public offering and sale of the Offered Securities to continue as contemplated in the registration statement that was the subject of the Rule 401(g)(2) notice or for which the Company has otherwise become ineligible. References herein to the Registration Statement shall include such new registration statement or post-effective amendment, as the case may be.

(D) Filing Fees. The Company has paid or shall pay the required Commission filing fees relating to the Offered Securities within the time required by Rule 456(b)(1) without regard to the proviso therein and otherwise in accordance with Rules 456(b) and 457(r).

(iv) Ineligible Issuer Status. (A) At the earliest time after the filing of the Registration Statement that the Company or another offering participant made a bona fide offer (within the meaning of Rule 164(h)(2)) of the Offered Securities and (B) at the date of this Agreement, the Company was not and is not an “ineligible issuer,” as defined in Rule 405.

(v) General Disclosure Package. As of the Applicable Time, neither (A) the General Use Issuer Free Writing Prospectus(es), if any, issued at or prior to the Applicable Time, the preliminary prospectus supplement, dated October 11, 2012, including the base prospectus, dated November 29, 2010 (which is the most recent Statutory Prospectus distributed to investors generally), and the other information, if any, stated in Schedule B to this Agreement to be included in the General Disclosure Package, all considered together (collectively, the “General Disclosure Package”), nor (B) any individual Limited Use Issuer Free Writing Prospectus, when considered together with the General Disclosure Package, included any untrue statement of a material fact or omitted to state any material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading. The preceding sentence does not apply to statements in or omissions from any Statutory Prospectus or any Issuer Free Writing Prospectus in reliance upon and in conformity with written information furnished to the Company by any Underwriter through the Representative specifically for use therein, it being understood and agreed that the only such information furnished by any Underwriter consists of the information described as such in Section 8(a) hereof.

(vi) Issuer Free Writing Prospectuses. Each Issuer Free Writing Prospectus, as of its issue date and at all subsequent times through the completion of the public offer and sale of the Offered Securities or until any earlier date that the Company notified or notifies Credit Suisse Securities (USA) LLC (“Credit Suisse”) as described in the next sentence, did not, does not and will not include any information that conflicted, conflicts or will conflict with the information then contained in the Registration Statement. If at any time following issuance of an Issuer Free Writing

Prospectus there occurred or occurs an event or development as a result of which such Issuer Free Writing Prospectus conflicted or would conflict with the information then contained in the Registration Statement or as a result of which such Issuer Free Writing Prospectus, if republished immediately following such event or development, would include an untrue statement of a material fact or omitted or would omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading, (A) the Company has promptly notified or will promptly notify Credit Suisse and (B) the Company has promptly amended or will promptly amend or supplement such Issuer Free Writing Prospectus to eliminate or correct such conflict, untrue statement or omission.

(vii) Good Standing of the Company. The Company has been duly incorporated and is validly existing and in good standing under the laws of the State of Delaware, with power and authority (corporate and other) to own its properties and conduct its business as described in the General Disclosure Package; and, except as would not, individually or in the aggregate, result in a material adverse change in the condition (financial or otherwise), results of operations, properties, business or prospects of the Company and its subsidiaries taken as a whole (a “Material Adverse Effect”), the Company is duly qualified to do business as a foreign corporation in good standing in all other jurisdictions in which its ownership or lease of property or the conduct of its business requires such qualification.

(viii) Subsidiaries. Each subsidiary of the Company has been duly incorporated and is a validly existing corporation in good standing under the laws of the jurisdiction of its incorporation, with power and authority (corporate and other) to own its properties and conduct its business as described in the General Disclosure Package; and, except as would not, individually or in the aggregate, result in a Material Adverse Effect, each subsidiary of the Company is duly qualified to do business as a foreign corporation in good standing in all other jurisdictions in which its ownership or lease of property or the conduct of its business requires such qualification; all of the issued and outstanding capital stock of each subsidiary of the Company has been duly authorized and validly issued and is fully paid and nonassessable; and the capital stock of each subsidiary owned by the Company, directly or through subsidiaries, is owned free from liens, encumbrances and defects.

(ix) Execution and Delivery of Indenture. The Indenture has been duly authorized and has been duly qualified under the Trust Indenture Act and the Base Indenture has been duly executed and delivered; the Offered Securities have been duly authorized and, when the Offered Securities are delivered and paid for pursuant to this Agreement on each Closing Date, the Supplemental Indenture will have been duly executed and delivered, such Offered Securities will have been duly executed, authenticated, issued and delivered, will conform to the information in the General Disclosure Package and to the description of such Offered Securities contained in the Final Prospectus and the Indenture and such Offered Securities will constitute valid and legally binding obligations of the Company, enforceable in accordance with their terms, subject to bankruptcy, insolvency, fraudulent transfer, reorganization, moratorium and similar laws of general applicability relating to or affecting creditors’ rights and to general equity principles.

(x) Offered Securities. When the Offered Securities are delivered and paid for pursuant to this Agreement on each Closing Date, such Offered Securities will be convertible into cash, the Underlying Shares of the Company or a combination thereof in accordance with the terms of the Indenture; the maximum number of Underlying Shares initially issuable upon conversion of such Offered Securities (including any Underlying Shares to be issued upon conversion of the Offered Securities in connection with a make-whole adjustment event or through operation of any

incremental share factor), assuming the Company elects to issue and deliver solely shares of Common Stock in respect of all such conversions, have been duly authorized and reserved for issuance upon such conversion, conform to the information in the General Disclosure Package and to the description of such Underlying Shares contained in the Final Prospectus; the authorized equity capitalization of the Company is as set forth in the General Disclosure Package; all outstanding shares of capital stock of the Company are, and when issued upon conversion any Underlying Shares will be validly issued, fully paid and nonassessable; the stockholders of the Company have no preemptive rights with respect to the Offered Securities or any Underlying Shares, and none of the outstanding shares of capital stock of the Company have been issued in violation of any preemptive or similar rights of any security holder.

(xi) No Finder’s Fee. Except as disclosed in the General Disclosure Package, there are no contracts, agreements or understandings between the Company and any person that would give rise to a valid claim against the Company or any Underwriter for a brokerage commission, finder’s fee or other like payment in connection with this offering.

(xii) Registration Rights. Except as disclosed in the General Disclosure Package, there are no contracts, agreements or understandings between the Company and any person granting such person the right to require the Company to file a registration statement under the Act with respect to any securities of the Company owned or to be owned by such person or to require the Company to include such securities in any securities being registered pursuant to any other registration statement filed by the Company under the Act (collectively, “registration rights”).

(xiii) Listing. On the Closing Date, the maximum number of Underlying Shares initially issuable upon conversion of the Offered Securities (including any Underlying Shares to be issued upon conversion of the Offered Securities in connection with a make-whole adjustment event or through operation of any incremental share factor), assuming the Company elects to issue and deliver solely shares of Common Stock in respect of all such conversions, will be approved for listing on the New York Stock Exchange and will be approved for listing on the Toronto Stock Exchange.

(xiv) Absence of Further Requirements. No consent, approval, authorization, order of or filing (other than Current Reports on Form 8-K and prospectus supplements relating to the Offered Securities required to be filed with the Commission) or registration with any person (including any governmental agency or body or any court) or consent, approval or authorization under the rules of the New York Stock Exchange or the Toronto Stock Exchange or approval of the stockholders of the Company or any third party is required to be obtained or made by the Company for issuance and sale by the Company of the Offered Securities to the Underwriters or the issuance of any Underlying Shares upon the conversion thereof, except such as have been obtained or made and such as may be required under state or provincial securities laws.

(xv) Absence of Defaults and Conflicts Resulting from Transaction. The execution, delivery and performance of this Agreement and the Indenture, and the consummation of the transactions herein and therein contemplated (including, without limitation, the issuance and sale of the Offered Securities to the Underwriters and the issuance of any Underlying Shares upon conversion thereof) will not (A) result in a breach or violation of any of the terms and provisions of, (B) constitute a default or a Debt Repayment Triggering Event (as defined below) under, (C) result in the imposition of any lien, charge or encumbrance upon any property or assets of the Company or any of its subsidiaries pursuant to (1) the charter or by-laws of the Company or any of its subsidiaries, (2) any statute, rule, regulation or order of any governmental agency or body or any court, domestic or foreign, having jurisdiction over the Company or any of

its subsidiaries or any of their properties or (3) any agreement or instrument to which the Company or any of its subsidiaries is a party or by which the Company or any of its subsidiaries is bound or to which any of the properties of the Company or any of its subsidiaries is subject, except in the case of clauses (2) and (3) for those which would not result in a Material Adverse Effect. A “Debt Repayment Triggering Event” means any event or condition that gives, or with the giving of notice or lapse of time would give, the holder of any note, debenture or other evidence of indebtedness (or any person acting on such holder’s behalf) the right to require the repurchase, redemption or repayment of all or a portion of such indebtedness by the Company or any of its subsidiaries.

(xvi) Absence of Existing Defaults and Conflicts. Neither the Company nor any of its subsidiaries is in violation of its respective charter or by-laws or in default (or with the giving of notice or lapse of time would be in default) under any existing obligation, agreement, covenant or condition contained in any indenture, loan agreement, mortgage, lease or other agreement or instrument to which any of them is a party or by which any of them is bound or to which any of the properties of any of them is subject, except such defaults that would not, individually or in the aggregate, result in a Material Adverse Effect.

(xvii) Authorization of Agreement. This Agreement has been duly authorized, executed and delivered by the Company.

(xviii) Title to Property. Except as disclosed in the General Disclosure Package, and except as would not, individually or in the aggregate, result in a Material Adverse Effect, the Company and its subsidiaries have good and marketable title to all real properties and all other properties and assets owned by them, in each case free from liens, charges, encumbrances and defects that would materially affect the value thereof or materially interfere with the use made or to be made thereof by them, and except as disclosed in the General Disclosure Package, the Company and its subsidiaries hold any leased real or personal property under valid and enforceable leases with no terms or provisions that would materially interfere with the use made or to be made thereof by them.

(xix) Possession of Licenses and Permits. Except as disclosed in the General Disclosure Package, and, in respect of non-U.S. Licenses only except as would not individually, or in the aggregate, result in a Material Adverse Effect, the Company and its subsidiaries possess, and are in compliance with the terms of, all adequate certificates, authorizations, franchises, licenses and permits (“Licenses”) necessary or material to the conduct of the business now conducted or proposed in the General Disclosure Package to be conducted by them and have not received any notice of proceedings relating to the revocation or modification of any Licenses that, if determined adversely to the Company or any of its subsidiaries, would individually or in the aggregate have a Material Adverse Effect.

(xx) Absence of Labor Dispute. No labor dispute with the employees of the Company or any of its subsidiaries exists or, to the knowledge of the Company, is imminent that could have a Material Adverse Effect.

(xxi) Possession of Intellectual Property. The Company and its subsidiaries own, possess or can acquire on reasonable terms, adequate trademarks, trade names and other rights to inventions, know-how, patents, copyrights, confidential information and other intellectual property (collectively, “intellectual property rights”) necessary to conduct the business now operated by them, or presently employed by them, and have not received any notice of infringement of or conflict with asserted rights of others with respect to any intellectual property rights that, if determined adversely to the Company or any of its subsidiaries, would individually or in the aggregate have a Material Adverse Effect.

(xxii) Environmental Laws. Except as disclosed in the General Disclosure Package, (A) (1) neither the Company nor any of its subsidiaries is in violation of, or has any liability under, any federal, state, local or non-U.S. statute, law, rule, regulation, ordinance, code, other requirement or rule of law (including common law), or decision or order of any domestic or foreign governmental agency, governmental body or court, relating to pollution, to the use, handling, transportation, treatment, storage, discharge, disposal or release of Hazardous Substances, to the protection or restoration of the environment or natural resources (including biota), to health and safety including as such relates to exposure to Hazardous Substances, and to natural resource damages (collectively, “Environmental Laws”), (2) neither the Company nor any of its subsidiaries owns, occupies, operates or uses any real property contaminated with Hazardous Substances, (3) neither the Company nor any of its subsidiaries is conducting or funding any investigation, remediation, remedial action or monitoring of actual or suspected Hazardous Substances in the environment, (4) neither the Company nor any of its subsidiaries is liable or allegedly liable for any release or threatened release of Hazardous Substances, including at any off-site treatment, storage or disposal site, (5) neither the Company nor any of its subsidiaries is subject to any claim by any governmental agency or governmental body or person relating to Environmental Laws or Hazardous Substances and (6) the Company and its subsidiaries have received and are in compliance with all, and have no liability under any, permits, licenses, authorizations, identification numbers or other approvals required under applicable Environmental Laws to conduct their respective businesses, except in each case covered by clauses (1) – (6) such as would not individually or in the aggregate have a Material Adverse Effect; (B) to the knowledge of the Company there are no facts or circumstances that would reasonably be expected to result in a violation of, liability under, or claim pursuant to any Environmental Law that would have a Material Adverse Effect; and (C) to the knowledge of the Company there are no requirements proposed for adoption or implementation under any Environmental Law that would reasonably be expected to have a Material Adverse Effect. For purposes of this subsection, “Hazardous Substances” means (i) petroleum and petroleum products, by-products or breakdown products, radioactive materials, asbestos-containing materials, polychlorinated biphenyls and mold and (ii) any other chemical, material or substance defined or regulated as toxic or hazardous or as a pollutant, contaminant or waste under Environmental Laws.

(xxiii) Litigation. Except as disclosed in the General Disclosure Package, there are no pending actions, suits or proceedings (including any inquiries or investigations by any court or governmental agency or body, domestic or foreign) against or affecting the Company, any of its subsidiaries or any of their respective properties that, if determined adversely to the Company or any of its subsidiaries, would individually or in the aggregate have a Material Adverse Effect, or that seeks to restrain, enjoin, prevent the consummation of or otherwise challenge the issuance or sale of the Offered Securities or any Underlying Shares to be sold hereunder; and no such actions, suits or proceedings (including any inquiries or investigations by any court or governmental agency or body, domestic or foreign) are, to the Company’s knowledge, threatened or contemplated.

(xxiv) Accurate Disclosure. The statements included or incorporated by reference in the General Disclosure Package and the Final Prospectus under the headings “Certain United States Federal Income Tax Considerations,” “Description of the Notes” and “Description of Capital Stock” and under the heading “Business—Regulatory and Environmental Matters” in the Company’s annual report on Form 10-K for the year ended December 31, 2011 and incorporated by reference in the General Disclosure Package and Final Prospectus insofar as such statements summarize legal matters,

agreements, documents or proceedings discussed therein, are accurate and fair summaries of such legal matters, agreements, documents or proceedings and present the information required to be shown. The Offered Securities, the Underlying Shares and the Indenture will conform in all material respects to the descriptions thereof in the General Disclosure Package and Final Prospectus.

(xxv) Absence of Manipulation. The Company has not taken, directly or indirectly, any action that is designed to or that has constituted or that would reasonably be expected to cause or result in the stabilization or manipulation of the price of any security of the Company to facilitate the sale or resale of the Offered Securities.

(xxvi) Financial Statements. The financial statements of the Company and its consolidated subsidiaries included or incorporated by reference in the Registration Statement and the General Disclosure Package present fairly the financial position of the Company and its consolidated subsidiaries as of the dates shown and their results of operations and cash flows for the periods shown, and such financial statements have been prepared in conformity with the generally accepted accounting principles in the United States (“U.S. GAAP”) applied on a consistent basis.

(xxvii) No Material Adverse Change in Business. Except as disclosed in the General Disclosure Package, since the end of the period covered by the latest audited financial statements included in the General Disclosure Package, (A) there has been no change, nor any development or event involving a prospective change, in the condition (financial or otherwise), results of operations, business or properties of the Company and its subsidiaries, taken as a whole, that is material and adverse, (B) except as disclosed in or contemplated by the General Disclosure Package, there has been no dividend or distribution of any kind declared, paid or made by the Company on any class of its capital stock and (C) except as disclosed in or contemplated by the General Disclosure Package, there has been no material adverse change in the capital stock, short-term indebtedness, long-term indebtedness, net current assets or net assets of the Company and its subsidiaries.

(xxviii) Investment Company Act. The Company is not and, after giving effect to the offering and sale of the Offered Securities, will not be an “investment company” as defined in the Investment Company Act of 1940, as amended (the “Investment Company Act”).

(xxix) Qualitative and Quantitative Data Regarding Proven and Probable Ore Reserves of the Company. The qualitative and quantitative data regarding proven and probable ore reserves of the Company included in the Registration Statement, a Statutory Prospectus or the General Disclosure Package (A) were derived in accordance with the procedures described in the Registration Statement, such Statutory Prospectus and the General Disclosure Package and, in all material respects, all applicable industry standards, including Securities Act Industry Guide 7 and National Instrument 43-101 of the Canadian securities administrators, and (B) have been reviewed by ▇▇▇▇▇ ▇▇▇▇▇▇▇ & Company (USA), Inc., with respect to the Stillwater Mine and East Boulder Mine, Micon International Limited, with respect to the Marathon Project, Python Mining Consultants Inc., with respect to the Geordie Lake PGM-Cu project, and P&E Mining Consultants Inc., with respect to the Bird River joint venture, each third-party independent geological experts.

(xxx) Statistical and Market-Related Data. Any third-party statistical and market-related data included or incorporated by reference in a Registration Statement, a Statutory Prospectus or the General Disclosure Package are based on or derived from sources that the Company believes to be reliable and accurate.

(xxxi) Internal Controls and Compliance with the ▇▇▇▇▇▇▇▇-▇▇▇▇▇ Act. Except as set forth in the General Disclosure Package, the Company, its subsidiaries and the Company’s Board of Directors (the “Board”) are in compliance with ▇▇▇▇▇▇▇▇-▇▇▇▇▇ and all applicable Exchange Rules. The Company maintains a system of internal controls, including, but not limited to, disclosure controls and procedures, internal controls over accounting matters and financial reporting, an internal audit function and legal and regulatory compliance controls (collectively, “Internal Controls”) that comply with the Securities Laws and are sufficient to provide reasonable assurances that (A) transactions are executed in accordance with management’s general or specific authorizations, (B) transactions are recorded as necessary to permit preparation of financial statements in conformity with U.S. GAAP and to maintain accountability for assets, (C) access to assets is permitted only in accordance with management’s general or specific authorization and (D) the recorded accountability for assets is compared with the existing assets at reasonable intervals and appropriate action is taken with respect to any differences. The Internal Controls are, or upon consummation of the offering of the Offered Securities will be, overseen by the Audit Committee (the “Audit Committee”) of the Board in accordance with Exchange Rules. The Company has not publicly disclosed or reported to the Audit Committee or the Board, and within the next 90 days the Company does not reasonably expect to publicly disclose or report to the Audit Committee or the Board, a significant deficiency, material weakness, change in Internal Controls or fraud involving management or other employees who have a significant role in Internal Controls (each, an “Internal Control Event”), any violation of, or failure to comply with, the Securities Laws, or any matter which, if determined adversely, would have a Material Adverse Effect.

(xxxii) Ratings. No “nationally recognized statistical rating organization,” as such term is defined for in Section 3(a)(62) of the Exchange Act, (A) has imposed (or has informed the Company that it is considering imposing) any condition (financial or otherwise) on the Company’s retaining any rating assigned to the Company or any securities of the Company or (B) has indicated to the Company that it is considering any of the actions described in Section 7(d)(ii) hereof.

(xxxiii) No Unlawful Payments. None of the Company, any of its subsidiaries or any director, officer, agent, employee or other person associated with or acting on behalf of the Company or any of its subsidiaries has (A) used any corporate funds for any unlawful contribution, gift, entertainment or other unlawful expense relating to political activity; (B) made any direct or indirect unlawful payment to any foreign or domestic government official or employee from corporate funds; (C) violated or is in violation of any provision of the Foreign Corrupt Practices Act of 1977; or (D) made any bribe, rebate, payoff, influence payment, kickback or other unlawful payment.

(xxxiv) Compliance with Money Laundering Laws. The operations of the Company and its subsidiaries are and have been conducted at all times in compliance with applicable financial recordkeeping and reporting requirements of the Currency and Foreign Transactions Reporting Act of 1970, as amended, the money laundering statutes of all jurisdictions, the rules and regulations thereunder and any related or similar rules, regulations or guidelines, issued, administered or enforced by any governmental agency (collectively, the “Money Laundering Laws”), and no action, suit or proceeding by or before any court or governmental agency, authority or body or any arbitrator involving the Company or any of its subsidiaries with respect to the Money Laundering Laws is pending or, to the knowledge of the Company, threatened.

(xxxv) Compliance with OFAC. None of the Company, any of its subsidiaries or any director, officer, agent, employee or affiliate of the Company or any of its subsidiaries is currently subject to any U.S. sanctions administered by the Office of Foreign Assets Control of the U.S. Department of the Treasury (“OFAC”).

(xxxvi) Taxes. The Company and each of its subsidiaries have filed all federal, state, local and foreign tax returns required to be filed through the date of this Agreement or have requested extensions thereof (except where the failure to file would not, individually or in the aggregate, reasonably be expected to have a Material Adverse Effect) and have paid all taxes required to be paid thereon (except for cases in which the failure to file or pay would not have a Material Adverse Effect, or, except as currently being contested in good faith and for which reserves required by U.S. GAAP have been created in the financial statements of the Company), and no tax deficiency has been determined adversely to the Company or any of its subsidiaries which has had (nor does the Company nor any of its subsidiaries have any notice or knowledge of any tax deficiency which would reasonably be expected to be determined adversely to the Company or its subsidiaries) which would, in either case, reasonably be expected to have a Material Adverse Effect.

(xxxvii) Insurance. The Company and its subsidiaries are insured by insurers with appropriately rated claims paying abilities against such losses and risks and in such amounts as are prudent and customary for the businesses in which they are engaged; all material policies of insurance insuring the Company or any of its subsidiaries or their respective businesses, assets, employees, officers and directors are in full force and effect.

(xxxviii) Margin Rules. None of the Company, its subsidiaries or any agent acting on their behalf has taken or will take any action that might cause this Agreement or the sale of the Notes or the Conversion Shares to violate Regulation T, U or X of the Board of Governors of the Federal Reserve System, in each case as in effect, or as the same may hereafter be in effect, on the Closing Date.

(xxxix) Solvency. Immediately after the consummation of the transactions contemplated by this Agreement, the fair value and present fair saleable value of the assets of each of the Company and its subsidiaries (each on a consolidated basis) will exceed the sum of its stated liabilities and identified contingent liabilities; none of the Company or its subsidiaries (each on a consolidated basis) is, nor will any of the Company or its subsidiaries (each on a consolidated basis) be, after giving effect to the execution, delivery and performance of this Agreement, and the consummation of the transactions contemplated hereby, (A) left with unreasonably small capital with which to carry on its business as it is proposed to be conducted, (B) unable to pay its debts (contingent or otherwise) as they mature or (C) otherwise insolvent.

(xl) Reporting Issuer Status. The Company is a reporting issuer (or the equivalent) in good standing in each of the Canadian provinces of British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, New Brunswick, Nova Scotia, ▇▇▇▇▇▇ ▇▇▇▇▇▇ Island and Newfoundland and Labrador under the applicable securities laws of each such jurisdiction and the respective regulations and rules made under those securities laws together with all applicable policy statements, blanket orders and rulings of the securities commissions of such jurisdictions and is in compliance with the applicable by-laws, rules and regulations of the Toronto Stock Exchange.

3. Purchase, Sale and Delivery of Offered Securities. (a) On the basis of the representations, warranties and agreements herein contained, but subject to the terms and conditions herein set forth, the Company agrees to sell to the Underwriters, and the Underwriters agree, severally and not jointly, to purchase from the Company, at a purchase price of 97.0% of the principal amount thereof, the respective principal amount of Firm Securities set forth opposite the names of the Underwriters in Schedule A hereto.

(b) The Company will deliver the Firm Securities to or as instructed by the Representative for the accounts of the several Underwriters in a form reasonably acceptable to the Representative against payment of the purchase price by the Underwriters in Federal (same day) funds by wire transfer to an account at a bank acceptable to Credit Suisse drawn to the order of the Company at the office of ▇▇▇▇▇ ▇▇▇▇ & ▇▇▇▇▇▇▇▇ LLP, ▇▇▇ ▇▇▇▇▇▇▇▇▇ ▇▇▇., ▇▇▇ ▇▇▇▇, ▇▇ ▇▇▇▇▇, at 10:00 A.M., New York time, on October 17, 2012, or at such other time not later than seven full business days thereafter as Credit Suisse and the Company determine, such time being herein referred to as the “First Closing Date.” For purposes of Rule 15c6-1 under the Exchange Act, the First Closing Date (if later than the otherwise applicable settlement date) shall be the settlement date for payment of funds and delivery of securities for all the Offered Securities sold pursuant to the offering. The Firm Securities so to be delivered or evidence of their issuance will be made available for checking at the above office of ▇▇▇▇▇ ▇▇▇▇ & ▇▇▇▇▇▇▇▇ LLP at least 24 hours prior to the First Closing Date.

(c) In addition, upon written notice from Credit Suisse given to the Company on from time to time not more than 30 days subsequent to the date of the Final Prospectus, the Underwriters may purchase all or less than all of the Optional Securities at the purchase price per principal amount of Securities (plus any accrued interest thereon to the Optional Closing Date) to be paid for the Firm Securities. The Company agrees to sell to the Underwriters the principal amount of Optional Securities specified in such notice, and the Underwriters agree, severally and not jointly, to purchase such Optional Securities. Such Optional Securities shall be purchased for the account of each Underwriter in the same proportion as the principal amount of Firm Securities set forth opposite such Underwriter’s name bears to the total principal amount of Firm Securities (subject to adjustment by Credit Suisse to eliminate fractions) and may be purchased by the Underwriters only for the purpose of covering over-allotments made in connection with the sale of the Firm Securities. No Optional Securities shall be sold or delivered unless the Firm Securities previously have been, or simultaneously are, sold and delivered. The right to purchase the Optional Securities or any portion thereof may be exercised from time to time to satisfy over-allotments and to the extent not previously exercised may be surrendered and terminated at any time upon notice by Credit Suisse to the Company.

(d) The time for the delivery of and payment for the Optional Securities, being herein referred to as the “Optional Closing Date,” which may be the First Closing Date (the First Closing Date and the Optional Closing Date, if any, being sometimes referred to as a “Closing Date”), shall be determined by Credit Suisse but shall be not later than five full business days after written notice of election to purchase Optional Securities is given. The Company will deliver the Optional Securities being purchased on the Optional Closing Date to or as instructed by Credit Suisse for the accounts of the several Underwriters in a form reasonably acceptable to Credit Suisse against payment of the purchase price therefor in federal (same day) funds by wire transfer to an account at a bank acceptable to the Representative drawn to the order of the Company at the above office of ▇▇▇▇▇ ▇▇▇▇ & ▇▇▇▇▇▇▇▇ LLP. The Optional Securities being purchased on the Optional Closing Date will be made available for checking at the above office of ▇▇▇▇▇ ▇▇▇▇ & ▇▇▇▇▇▇▇▇ LLP at a reasonable time in advance of the Optional Closing Date.

4. Offering by Underwriters. It is understood that the several Underwriters propose to offer the Offered Securities for sale to the public as set forth in the Final Prospectus.

5. Certain Agreements of the Company. (a) The Company agrees with the several Underwriters that:

(i) Filing of Prospectuses. The Company has filed or will file each Statutory Prospectus (including the Final Prospectus) pursuant to and in accordance with Rule 424(b)(2) (or, if applicable and consented to by Credit Suisse, subparagraph (5)) not later than the second business day following the earlier of the date it is first used or the execution and delivery of this Agreement. The Company has complied and will comply with Rule 433.

(ii) Filing of Amendments; Response to Commission Requests. At any time when a prospectus relating to the Offered Securities is (or but for the exemption in Rule 172 under the Act would be) required to be delivered under the Act by any Underwriter or dealer, the Company will promptly advise Credit Suisse of any proposal to amend or supplement the Registration Statement or any Statutory Prospectus at any time and will offer Credit Suisse a reasonable opportunity to comment on any such amendment or supplement; and the Company will also advise Credit Suisse promptly of (A) the filing of any such amendment or supplement, (B) any request by the Commission or its staff for any amendment to the Registration Statement, for any supplement to any Statutory Prospectus or for any additional information, (C) the institution by the Commission of any stop order proceedings in respect of the Registration Statement or the threatening of any proceeding for that purpose and (D) the receipt by the Company of any notification with respect to the suspension of the qualification of the Offered Securities in any jurisdiction or the institution or threatening of any proceedings for such purpose. The Company will use its reasonable best efforts to prevent the issuance of any such stop order or the suspension of any such qualification and, if issued, to obtain as soon as possible the withdrawal thereof.

(iii) Continued Compliance with Securities Laws. If, at any time when a prospectus relating to the Offered Securities is (or but for the exemption in Rule 172 would be) required to be delivered under the Act by any Underwriter or dealer, any event occurs as a result of which the Final Prospectus as then amended or supplemented would include an untrue statement of a material fact or omit to state any material fact necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading, or if it is necessary at any time to amend the Registration Statement or supplement the Final Prospectus to comply with the Act, the Company will promptly notify Credit Suisse of such event and will promptly prepare and file with the Commission and furnish, at its own expense, to the Underwriters and the dealers and any other dealers upon request of Credit Suisse, an amendment or supplement which will correct such statement or omission or an amendment which will effect such compliance. Neither Credit Suisse’s consent to, nor the Underwriters’ delivery of, any such amendment or supplement shall constitute a waiver of any of the conditions set forth in Section 7 hereof.

(iv) Rule 158. As soon as practicable, but not later than 16 months, after the date of this Agreement, the Company will make generally available to its securityholders an earnings statement covering a period of at least 12 months beginning after the date of this Agreement and satisfying the provisions of Section 11(a) of the Act and Rule 158.

(v) Furnishing of Prospectuses. The Company will furnish to the Representative copies of the Registration Statement, including all exhibits, any Statutory Prospectus, the Final Prospectus and all amendments and supplements to such documents, in each case as soon as available and in such quantities as the Representative reasonably requests. The Company will pay the expenses of printing and distributing to the Underwriters all such documents.

(vi) Qualification of the Offered Securities. The Company will arrange for the qualification of the Offered Securities for sale and the determination of their eligibility for investment under the laws of such jurisdictions as Credit Suisse designates and will continue such qualifications in effect so long as required for the distribution; provided that in no event shall the Company be obligated to (i) qualify to do business in any jurisdiction where it is not now so qualified, (ii) take any action that would subject it to service of process in suits, other than those arising out of the offering or sale of the Offered Securities, in any jurisdiction where it is not now subject or (iii) subject itself to taxation in any jurisdiction in which it would not otherwise be subject.

(vii) Reporting Requirements. During the period of three years hereafter, the Company will furnish to the Representative and, upon request, to each of the other Underwriters, as soon as practicable after the end of each fiscal year, a copy of its annual report to stockholders for such year; and the Company will furnish to the Representative (A) as soon as available, a copy of each report and any definitive proxy statement of the Company filed with the Commission under the Exchange Act or mailed to stockholders and (B) from time to time, such other information concerning the Company as the Representative may reasonably request. However, so long as the Company is subject to the reporting requirements of either Section 13 or Section 15(d) of the Exchange Act and is timely filing reports with the Commission on its Electronic Data Gathering, Analysis and Retrieval system (“▇▇▇▇▇”), it is not required to furnish any such reports or statements to the Underwriters.

(viii) DTC. The Company will use its best efforts to permit the Offered Securities to be eligible for clearance and settlement through The Depository Trust Company.

(ix) Reservation of Conversion Shares. The Company will reserve and keep available at all times, free of preemptive rights, the maximum number of Underlying Shares initially issuable upon conversion of the Offered Securities (including any Underlying Shares to be issued upon conversion of the Offered Securities in connection with a make-whole adjustment event or through operation of any incremental share factor), assuming the Company elects to issue and deliver solely shares of Common Stock in respect of all such conversions.

(x) No Actions Resulting in Adjustment of Conversion Rate. Between the date hereof and the First Closing Date, or the Optional Closing Date, if applicable, the Company will not do or authorize any act or thing that would result in an adjustment of the conversion rate.

(xi) Company Lock-Up. For the period specified below (the “Lock-Up Period”) the Company will not offer, sell, contract to sell, pledge or otherwise dispose of, directly or indirectly, except as provided hereunder, any securities of the Company (or guaranteed by the Company) that are substantially similar to the Securities, or any Securities, and the Company will not offer, sell, contract to sell, pledge or otherwise dispose of, directly or indirectly, or file with the Commission a registration statement under the Act relating to, any shares of Common Stock or securities convertible into or exchangeable or exercisable for any shares of Common Stock or the Securities, or publicly disclose the intention to make any such offer, sale, pledge, disposition or filing, without the prior written consent of Credit Suisse; provided, that the foregoing shall not apply to (A) the sale of Securities under this Agreement or the offering or issuance of any Underlying Shares upon conversion of the Offered Securities; (B) the issuance of restricted stock units and performance-based awards under the Company’s equity compensation plans and incentive retention plans described in the General Disclosure Package and the Final Prospectus; (C) the issuance of Common Stock pursuant to the vesting or exercise of equity awards, restricted stock units or performance based awards, including such awards issued as described in clause (B); (D) the filing of any registration statement on Form S-8 or any successor forms thereto relating solely to any of the Company’s employee benefit plans described in the General Disclosure Package and the Final Prospectus; (E) any issuance of Securities to the holders of the Company’s 1.875% Convertible Senior Notes due 2028 (the “Notes”) pursuant to the terms of the Notes. The initial Lock-Up Period will commence on the date hereof and will continue and include the date 60 days after the date hereof or such earlier date that Credit Suisse consents to in writing; provided, however, that if (A) during the last 17 days of the initial Lock-Up Period, the Company releases earnings results or material news or a material event relating to the Company occurs or (B) prior to the expiration of the initial Lock-Up

Period, the Company announces that it will release earnings results during the 16-day period beginning on the last day of the initial Lock-Up Period, then in each case the Lock-Up Period will be extended until the expiration of the 18-day period beginning on the date of release of the earnings results or the occurrence of the material news or material event, as applicable, unless Credit Suisse Securities (USA) LLC waives, in writing, such extension. The Company will provide the Representatives with notice of any announcement described in clause (B) of the preceding sentence that gives rise to an extension of the Lock-Up Period.

(xii) Enforcement of Lock-Up. The Company will take reasonable steps to enforce all agreements between the Company and any of its security holders to be entered into pursuant to this Agreement that prohibit the sale, transfer, assignment, pledge or hypothecation of any of the Company’s securities. In addition, the Company will direct the transfer agent to place stop transfer restrictions upon any such securities of the Company that are bound by such “lock-up” agreements for the duration of the periods contemplated in such agreements.

(xiii) Expenses of the Offering. The Company agrees to pay all costs and expenses incident to the performance of its obligations under this Agreement, whether or not the transactions contemplated herein are consummated or this Agreement is terminated, including all costs and expenses incident to (A) the printing, word processing or other production of documents with respect to the transactions contemplated hereby, including any costs of printing preliminary prospectuses, the Final Prospectus and any Issuer Free Writing Prospectus, and any amendments or supplements thereto, and any “Blue Sky” memoranda, (B) all arrangements relating to the delivery to the Underwriters of copies of the foregoing documents, (C) the fees and disbursements of the counsel, the accountants and any other experts or advisors retained by the Company, (D) preparation (including printing), issuance and delivery to the Underwriters of the Offered Securities, including any transfer taxes or any stamp or other duties payable upon the sale, issuance and delivery of the Offered Securities, (E) the qualification of the Offered Securities and Underlying Shares under state securities and “Blue Sky” laws, including filing fees and fees and disbursements of counsel for the Underwriters relating thereto, (F) expenses in connection with the “roadshow” and any other meetings with prospective investors in the Offered Securities, (G) fees and expenses of the Trustee including fees and expenses of counsel, (H) the fees and expenses associated with listing the Underlying Shares on the New York Stock Exchange and the Toronto Stock Exchange and (I) any fees charged by investment rating agencies for the rating of the Offered Securities; provided, however, except as set forth in this Agreement, the Underwriters shall pay their own costs and expenses, including fees of their counsel.

(xiv) Use of Proceeds. The Company will use the net proceeds received in connection with this offering in the manner described in the “Use of Proceeds” section of the General Disclosure Package and, except as disclosed in the General Disclosure Package, the Company does not intend to use any of the proceeds from the sale of the Offered Securities hereunder to repay any outstanding debt owed to any affiliate of any Underwriter.

(xv) Absence of Manipulation. The Company will not take, directly or indirectly, any action designed to or that would constitute or that might reasonably be expected to cause or result in, stabilization or manipulation of the price of any securities of the Company to facilitate the sale or resale of the Offered Securities.

6. Free Writing Prospectuses. (a) Issuer Free Writing Prospectuses. The Company represents and agrees that, unless it obtains the prior consent of Credit Suisse, and each Underwriter represents and agrees that, unless it obtains the prior consent of the Company and Credit Suisse, it has not

made and will not make any offer relating to the Offered Securities that would constitute an Issuer Free Writing Prospectus, or that would otherwise constitute a “free writing prospectus,” as defined in Rule 405, required to be filed with the Commission. Any such free writing prospectus consented to by the Company and Credit Suisse is hereinafter referred to as a “Permitted Free Writing Prospectus.” The Company represents that it has treated and agrees that it will treat each Permitted Free Writing Prospectus as an “issuer free writing prospectus,” as defined in Rule 433, and has complied and will comply with the requirements of Rules 164 and 433 applicable to any Permitted Free Writing Prospectus, including timely Commission filing where required, legending and record keeping.

(b) Term Sheets. The Company will prepare a final term sheet relating to the Offered Securities, containing only information that describes the final terms of the Offered Securities and otherwise in a form consented to by Credit Suisse, and will file such final term sheet within the period required by Rule 433(d)(5)(ii) following the date such final terms have been established for the offering of the Offered Securities. Any such final term sheet is an Issuer Free Writing Prospectus and a Permitted Free Writing Prospectus for purposes of this Agreement. The Company also consents to the use by any Underwriter of a free writing prospectus that contains only (i)(x) information describing the preliminary terms of the Offered Securities or their offering or (y) information that describes the final terms of the Offered Securities or their offering and that is included in the final term sheet of the Company contemplated in the first sentence of this subsection or (ii) other information that is not “issuer information,” as defined in Rule 433, it being understood that any such free writing prospectus referred to in clause (i) or (ii) above shall not be an Issuer Free Writing Prospectus for purposes of this Agreement.

7. Conditions of the Obligations of the Underwriters. The obligations of the several Underwriters to purchase and pay for the Firm Securities on the First Closing Date and the Optional Securities to be purchased on the Optional Closing Date will be subject to the accuracy of the representations and warranties of the Company herein (as though made on such Closing Date), to the accuracy of the statements of Company officers made pursuant to the provisions hereof, to the performance by the Company of its obligations hereunder and to the following additional conditions precedent:

(a) Accountants’ Comfort Letter. The Representative shall have received a letter, dated the date of this Agreement, of KPMG LLP confirming that they are independent public accountants within the meaning of the Act and the applicable published Rules and Regulations thereunder and substantially in the form attached hereto as Schedule C.

(b) Reserve Engineers’ Comfort Letter – Company. The Representative shall have received a letter, dated the date of this Agreement, of ▇▇▇▇▇ ▇▇▇▇▇▇▇ & Company (USA), Inc. in the form attached hereto as Schedule D.

(c) Filing of Prospectuses. The Company shall have filed each Statutory Prospectus (including the Final Prospectus) pursuant to and in accordance with Rule 424(b)(2) (or, if applicable and consented to by the Representative, subparagraph (5)) not later than the second business day following the earlier of the date it is first used or the execution and delivery of this Agreement. The Company has complied and will comply with Rule 433.

(d) No Material Adverse Change. Subsequent to the execution and delivery of this Agreement, there shall not have occurred (i) any change, or any development or event involving a prospective change, in the condition (financial or other), business, properties or results of operations of the Company or its subsidiaries which, in the judgment of the Representative, is material and adverse and makes it impractical or inadvisable to proceed with completion of the public offering or the sale of and payment for the Offered Securities; (ii) any downgrading in the rating of any debt securities of the Company by any “nationally recognized statistical rating organization” (as such term is defined in Section 3(a)(62) of the Exchange Act), or any public announcement that any such organization has under surveillance or review its rating of any debt securities of the Company (other than an announcement with positive implications of a possible upgrading, and no implication of a possible downgrading, of such rating); (iii) any change in U.S.

or international financial, political or economic conditions or currency exchange rates or exchange controls as would, in the judgment of the Representative, be likely to prejudice materially the success of the proposed issue, sale or distribution of the Offered Securities, whether in the primary market or in respect of dealings in the secondary market; (iv) any material suspension or material limitation of trading in securities generally on the New York Stock Exchange or any setting of minimum prices for trading on such exchange; (v) or any suspension of trading of any securities of the Company on any exchange or in the over-the-counter market; (vi) any banking moratorium declared by U.S. federal or New York authorities; (vii) any major disruption of settlements of securities or clearance services in the United States or (viii) any attack on, outbreak or escalation of hostilities or act of terrorism involving the United States, any declaration of war by Congress or any other national or international calamity or emergency if, in the judgment of the Representative, the effect of any such attack, outbreak, escalation, act, declaration, calamity or emergency makes it impractical or inadvisable to proceed with completion of the public offering or the sale of and payment for the Offered Securities.

(e) Opinions of Counsel for the Company. The Representative shall have received an opinion, dated such Closing Date, of Skadden, Arps, Slate, ▇▇▇▇▇▇▇ & ▇▇▇▇ LLP, counsel for the Company, in the form attached hereto as Schedule E-1. The Representative shall have received an opinion, dated such Closing Date, of ▇▇▇▇▇ ▇▇▇▇▇▇, Deputy General Counsel to the Company, in the form attached hereto as Schedule E-2. The Representative shall have received a negative assurance letter, dated such Closing Date, of Skadden, Arps, Slate, ▇▇▇▇▇▇▇ & ▇▇▇▇ LLP, counsel for the Company, in the form attached hereto as Schedule E-3.

(f) Opinion of Counsel for Underwriters. The Representative shall have received from ▇▇▇▇▇ ▇▇▇▇ & ▇▇▇▇▇▇▇▇ LLP, counsel for the Underwriters, such opinion or opinions, dated such Closing Date, with respect to such matters as the Representative may require, and the Company shall have furnished to such counsel such documents as they request for the purpose of enabling them to pass upon such matters.

(g) Officer’s Certificate – Company. The Representative shall have received a certificate, dated such Closing Date, of the President or any Vice President and a principal financial or accounting officer of the Company in which such officers shall state that, to the best of their knowledge after reasonable investigation: the representations and warranties of the Company in this Agreement are true and correct; the Company has complied with all agreements and satisfied all conditions on its part to be performed or satisfied hereunder at or prior to such Closing Date; the sale of the Offered Securities and Underlying Shares hereunder has not been enjoined (temporarily or permanently); no stop order suspending the effectiveness of any Registration Statement has been issued and no proceedings for that purpose have been instituted or are contemplated by the Commission; and, subsequent to the date of the most recent financial statements in the General Disclosure Package, there has been no material adverse change, nor any development or event involving a prospective material adverse change, in the condition (financial or other), business, properties or results of operations of the Company and its subsidiaries taken as a whole except as set forth in the General Disclosure Package or as described in such certificate.

(h) Bring-down Accountants’ Comfort Letter. The Representative shall have received a letter, dated such Closing Date, of KPMG LLP which meets the requirements of subsection (a) of this Section, except that the specified date referred to in such subsection will be a date not more than three days prior to such Closing Date for the purposes of this subsection.

(i) Bring-down Reserve Engineers’ Comfort Letter – Company. The Representative shall have received a letter, dated such Closing Date, of ▇▇▇▇▇ ▇▇▇▇▇▇▇ & Company (USA), Inc. which meets the requirements of subsection (b) of this Section, except that the specified date referred to in such subsection will be a date not more than three days prior to such Closing Date for the purposes of this subsection.

(j) Lock-Up Agreements. On or prior to the date hereof, the Representative shall have received lock-up letters from each of the executive officers and directors of the Company, substantially in the form of Schedule F hereto.

The Company will furnish the Representative with such conformed copies of such opinions, certificates, letters and documents as the Representative reasonably requests. The Representative may in its sole discretion waive on behalf of the Underwriters compliance with any conditions to the obligations of the Underwriters hereunder, whether in respect of the Optional Closing Date or otherwise.

8. Indemnification and Contribution. (a) The Company will indemnify and hold harmless each Underwriter, its partners, members, directors, officers and affiliates and each person, if any, who controls such Underwriter within the meaning of Section 15 of the Act or Section 20 of the Exchange Act (each, an “Indemnified Party”), against any losses, claims, damages or liabilities, joint or several, to which such Indemnified Party may become subject, under the Act, the Exchange Act or otherwise, insofar as such losses, claims, damages or liabilities (or actions in respect thereof) arise out of or are based upon any untrue statement or alleged untrue statement of any material fact contained in any part of the Registration Statement at any time, any Statutory Prospectus as of any time, the Final Prospectus or any Issuer Free Writing Prospectus, or arise out of or are based upon the omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading, and will reimburse each Indemnified Party for any legal or other expenses reasonably incurred by such Indemnified Party in connection with investigating or defending any such loss, claim, damage, liability or action as such expenses are incurred; provided, however, that the Company will not be liable in any such case to the extent that any such loss, claim, damage or liability arises out of or is based upon an untrue statement or alleged untrue statement in or omission or alleged omission from any of such documents in reliance upon and in conformity with written information furnished to the Company by any Underwriter through the Representative specifically for use therein, it being understood and agreed that the only such information furnished by any Underwriter consists of the information described as such in subsection (a) below.

(b) Each Underwriter will severally and not jointly indemnify and hold harmless the Company, its directors and officers and each person, if any, who controls the Company within the meaning of Section 15 of the Act or Section 20 of the Exchange Act (each, an “Underwriter Indemnified Party”) against any losses, claims, damages or liabilities to which such Underwriter Indemnified Party may become subject, under the Act, the Exchange Act or otherwise, insofar as such losses, claims, damages or liabilities (or actions in respect thereof) arise out of or are based upon any untrue statement or alleged untrue statement of any material fact contained in any part of the Registration Statement at any time, any Statutory Prospectus as of any time, the Final Prospectus or any Issuer Free Writing Prospectus, or arise out of or are based upon the omission or the alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading, in each case to the extent, but only to the extent, that such untrue statement or alleged untrue statement or omission or alleged omission was made in reliance upon and in conformity with written information furnished to the Company by such Underwriter through the Representative specifically for use therein, and will reimburse any legal or other expenses reasonably incurred by such Underwriter Indemnified Party in connection with investigating or defending any such loss, claim, damage, liability or action as such expenses are incurred, it being understood and agreed that the only such information furnished by any Underwriter consists of the following information in the Final Prospectus furnished on behalf of each Underwriter: the concession figure appearing in the fourth paragraph under the caption “Underwriting” and the information contained in the fourteenth paragraph under the caption “Underwriting.”

(c) Promptly after receipt by an indemnified party under this Section of notice of the commencement of any action, such indemnified party will, if a claim in respect thereof is to be made against the indemnifying party under subsection (a) or (b) above, notify the indemnifying party of the commencement thereof; but the failure to notify the indemnifying party shall not relieve it from any liability that it may have under subsection (a) or (b) above except

to the extent that it has been materially prejudiced (through the forfeiture of substantive rights or defenses) by such failure; and provided further that the failure to notify the indemnifying party shall not relieve it from any liability that it may have to an indemnified party otherwise than under subsection (a) or (b) above. In case any such action is brought against any indemnified party and it notifies the indemnifying party of the commencement thereof, the indemnifying party will be entitled to participate therein, and, to the extent that it may wish with the consent of the Representative on behalf of the Underwriters such consent not to be unreasonably withheld (if an Underwriter is an indemnified party), jointly with any other indemnifying party similarly notified, to assume the defense thereof, with counsel satisfactory to such indemnified party (who shall not, except with the consent of the indemnified party, be counsel to the indemnifying party), and after notice from the indemnifying party to such indemnified party of its election so to assume the defense thereof, the indemnifying party will not be liable to such indemnified party under this Section 8 for any legal or other expenses subsequently incurred by such indemnified party in connection with the defense thereof other than reasonable costs of investigation. No indemnifying party shall, without the prior written consent of the indemnified party, effect any settlement of any pending or threatened action in respect of which any indemnified party is or could have been a party and indemnity could have been sought hereunder by such indemnified party unless such settlement a) includes an unconditional release of such indemnified party from all liability on any claims that are the subject matter of such action and b) does not include a statement as to, or an admission of, fault, culpability or a failure to act by or on behalf of an indemnified party.

(d) If the indemnification provided for in this Section 8 is unavailable or insufficient to hold harmless an indemnified party under subsection (a) or (b) above, then each indemnifying party shall contribute to the amount paid or payable by such indemnified party as a result of the losses, claims, damages or liabilities referred to in subsection (a) or (b) above (i) in such proportion as is appropriate to reflect the relative benefits received by the Company on the one hand and the Underwriters on the other from the offering of the Securities or (ii) if the allocation provided by clause (i) above is not permitted by applicable law, in such proportion as is appropriate to reflect not only the relative benefits referred to in clause (i) above but also the relative fault of the Company on the one hand and the Underwriters on the other in connection with the statements or omissions which resulted in such losses, claims, damages or liabilities as well as any other relevant equitable considerations. The relative benefits received by the Company on the one hand and the Underwriters on the other shall be deemed to be in the same proportion as the total net proceeds from the offering (before deducting expenses) received by the Company bear to the total underwriting discounts and commissions received by the Underwriters. The relative fault shall be determined by reference to, among other things, whether the untrue or alleged untrue statement of a material fact or the omission or alleged omission to state a material fact relates to information supplied by the Company or the Underwriters and the parties’ relative intent, knowledge, access to information and opportunity to correct or prevent such untrue statement or omission. The amount paid by an indemnified party as a result of the losses, claims, damages or liabilities referred to in the first sentence of this subsection (d) shall be deemed to include any legal or other expenses reasonably incurred by such indemnified party in connection with investigating or defending any action or claim which is the subject of this subsection (d). Notwithstanding the provisions of this subsection (d), no Underwriter shall be required to contribute any amount in excess of the amount by which the total price at which the Offered Securities underwritten by it and distributed to the public were offered to the public exceeds the amount of any damages which such Underwriter has otherwise been required to pay by reason of such untrue or alleged untrue statement or omission or alleged omission. No person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Act) shall be entitled to contribution from any person who was not guilty of such fraudulent misrepresentation. The Underwriters’ obligations in this subsection (d) to contribute are several in proportion to their respective underwriting obligations and not joint.

(e) The obligations of the Company under this Section 8 shall be in addition to any liability which the Company may otherwise have and shall extend, upon the same terms and conditions, to each person, if any, who controls any Underwriter within the meaning of the Act;

and the obligations of the Underwriters under this Section 8 shall be in addition to any liability which the respective Underwriters may otherwise have and shall extend, upon the same terms and conditions, to each director of the Company, to each officer of the Company and to each person, if any, who controls the Company within the meaning of the Act.

9. Default of Underwriters. If any Underwriter or Underwriters default in their obligations to purchase Offered Securities hereunder on either the First Closing Date or the Optional Closing Date and the aggregate principal amount of Offered Securities that such defaulting Underwriter or Underwriters agreed but failed to purchase does not exceed 10% of the total principal amount of Offered Securities that the Underwriters are obligated to purchase on such Closing Date, Credit Suisse may make arrangements satisfactory to the Company for the purchase of such Offered Securities by other persons, including any of the Underwriters, but if no such arrangements are made by such Closing Date, the non-defaulting Underwriters shall be obligated severally, in proportion to their respective commitments hereunder, to purchase the Offered Securities that such defaulting Underwriters agreed but failed to purchase on such Closing Date. If any Underwriter or Underwriters so default and the aggregate principal amount of Offered Securities with respect to which such default or defaults occur exceeds 10% of the total principal amount of Offered Securities that the Underwriters are obligated to purchase on such Closing Date and arrangements satisfactory to Credit Suisse and the Company for the purchase of such Offered Securities by other persons are not made within 36 hours after such default, this Agreement will terminate without liability on the part of any non-defaulting Underwriter or the Company, except as provided in Section 10, (provided that if such default occurs with respect to Optional Securities after the First Closing Date, this Agreement will not terminate as to the Firm Securities or any Optional Securities purchased prior to such termination). As used in this Agreement, the term “Underwriter” includes any person substituted for an Underwriter under this Section 9. Nothing herein will relieve a defaulting Underwriter from liability for its default.

10. Survival of Certain Representations and Obligations. The respective indemnities, agreements, representations, warranties and other statements of the Company or its officers and of the several Underwriters set forth in or made pursuant to this Agreement will remain in full force and effect, regardless of any investigation, or statement as to the results thereof, made by or on behalf of any Underwriter, the Company or any of their respective representatives, officers or directors or any controlling person, and will survive delivery of and payment for the Offered Securities. If the purchase of the Offered Securities by the Underwriters is not consummated for any reason other than solely because of the termination of this Agreement pursuant to Section 9 hereof, the Company will reimburse the Underwriters for all out-of-pocket expenses (including fees and disbursements of counsel) reasonably incurred by them in connection with the offering of the Offered Securities, and the respective obligations of the Company and the Underwriters pursuant to Section 8 hereof shall remain in effect, and if any Offered Securities have been purchased hereunder, the representations and warranties in Section 2 and all obligations under Section 5 shall also remain in effect.

11. Notices. All communications hereunder will be in writing and, if sent to the Underwriters, will be mailed, delivered or telegraphed and confirmed to the Representative at Credit Suisse Securities (USA) LLC, Eleven Madison Avenue, New York, N.Y. 10010-3629, Attention: Transactions Advisory Group; or, if sent to the Company, will be mailed, delivered or telegraphed and confirmed to it at ▇▇▇▇ ▇▇▇▇▇▇▇▇▇ ▇▇▇▇▇, ▇▇▇▇▇▇▇▇, ▇▇ ▇▇▇▇▇, Attention: ▇▇▇▇▇ ▇▇▇▇▇▇; provided, however, that any notice to an Underwriter pursuant to Section 8 will be mailed, delivered or telegraphed and confirmed to such Underwriter.

12. Successors. This Agreement will inure to the benefit of and be binding upon the parties hereto and their respective successors and the officers and directors and controlling persons referred to in Section 8, and no other person will have any right or obligation hereunder.

13. Representation. The Representative will act for the several Underwriters in connection with the transactions contemplated by this Agreement, and any action under this Agreement taken by Credit Suisse will be binding upon all the Underwriters.

14. Counterparts. This Agreement may be executed in any number of counterparts, each of which shall be deemed to be an original, but all such counterparts shall together constitute one and the same Agreement.

15. Absence of Fiduciary Relationship. The Company acknowledges and agrees that:

(a) No Other Relationship. The Representative has been retained solely to act as underwriter in connection with the sale of Offered Securities and that no fiduciary, advisory or agency relationship between the Company and the Representative has been created in respect of any of the transactions contemplated by this Agreement or the Final Prospectus, irrespective of whether the Representative has advised or is advising the Company on other matters;

(b) Arms’ Length Negotiations. The price of the Offered Securities set forth in this Agreement was established by the Company following discussions and arms-length negotiations with the Representative and the Company is capable of evaluating and understanding and understands and accepts the terms, risks and conditions of the transactions contemplated by this Agreement;

(c) Absence of Obligation to Disclose. The Company has been advised that the Representative and its affiliates are engaged in a broad range of transactions which may involve interests that differ from those of the Company and that the Representative has no obligation to disclose such interests and transactions to the Company by virtue of any fiduciary, advisory or agency relationship; and

(d) Waiver. The Company waives, to the fullest extent permitted by law, any claims it may have against the Representative for breach of fiduciary duty or alleged breach of fiduciary duty and agrees that the Representative shall have no liability (whether direct or indirect) to the Company in respect of such a fiduciary duty claim or to any person asserting a fiduciary duty claim on behalf of or in right of the Company, including stockholders, employees or creditors of the Company.

16. Applicable Law. This Agreement shall be governed by, and construed in accordance with, the laws of the State of New York.

17. The Company hereby submits to the non-exclusive jurisdiction of the Federal and state courts in the Borough of Manhattan in The City of New York in any suit or proceeding arising out of or relating to this Agreement or the transactions contemplated hereby. The Company irrevocably and unconditionally waives any objection to the laying of venue of any suit or proceeding arising out of or relating to this Agreement or the transactions contemplated hereby in Federal and state courts in the Borough of Manhattan in The City of New York and irrevocably and unconditionally waives and agrees not to plead or claim in any such court that any such suit or proceeding in any such court has been brought in an inconvenient forum.

If the foregoing is in accordance with the Representative’s understanding of our agreement, kindly sign and return to the Company one of the counterparts hereof, whereupon it will become a binding agreement between the Company and the several Underwriters in accordance with its terms.


STILLWATER MINING COMPANY

By		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇▇▇▇
Name:		▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇▇▇▇
Title:		Chairman and Chief Executive Officer


The foregoing Underwriting Agreement is hereby confirmed and accepted as of the date first above written.

CREDIT SUISSE SECURITIES (USA) LLC ▇▇▇▇▇ FARGO SECURITIES, LLC

Acting on behalf of themselves and as the Representative of the several Underwriters.

By CREDIT SUISSE SECURITIES (USA) LLC

By		/s/ ▇▇▇▇ ▇. ▇▇▇▇▇▇▇▇
		Name: ▇▇▇▇ ▇. ▇▇▇▇▇▇▇▇
		Title: Managing Director

By ▇▇▇▇▇ FARGO SECURITIES, LLC

By		/s/ ▇▇▇▇▇ ▇▇▇▇▇▇
		Name: ▇▇▇▇▇ ▇▇▇▇▇▇
		Title: Director

SCHEDULE A


Underwriter	Principal Amount of Firm Securities to be Purchased
Credit Suisse Securities (USA) LLC	$	241,500,000
▇▇▇▇▇ Fargo Securities, LLC		103,500,000

Total	$	345,000,000

A-1

SCHEDULE B

1.	General Use Issuer Free Writing Prospectuses (included in the General Disclosure Package)

“General Use Issuer Free Writing Prospectus” includes each of the following documents:

1. Final Term Sheet, dated as of October 11, 2012, a copy of which is attached hereto.

2.	Other Information Included in the General Disclosure Package

The following information is also included in the General Disclosure Package:

None.

B-1

STILLWATER MINING COMPANY

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