STILLWATER MINING COMPANY TECHNICAL REPORT FOR THE MINING OPERATIONS AT STILLWATER MINING COMPANY STILLWATER MINE, 45°23'N, 109°53'W EAST BOULDER MINE, 45°30'N, 109°05'W (BEHRE DOLBEAR PROJECT 11-030) MARCH 2011 PREPARED BY: MR. DAVID M. ABBOTT, JR., CPG DR. RICHARD L. BULLOCK, P.E. MS. BETTY GIBBS MR. RICHARD S. KUNTER BEHRE DOLBEAR & COMPANY, LTD. 999 Eighteenth Street, Suite 1500 Denver, Colorado 80202 (303) 620-0020 A Member of the Behre Dolbear Group Inc. © 2011, Behre Dolbear Group Inc. All Rights Reserved. www.dolbear.com Technical Report for the Mining Operations at Stillwater Mining Company March 2011 TABLE OF CONTENTS 3.0 SUMMARY ..................................................................................................................................... 1 3.1 INTRODUCTION .............................................................................................................. 1 3.2 EXPLORATION ................................................................................................................ 1 3.3 GEOLOGY AND MINERALIZATION ............................................................................ 2 3.4 DRILLING, SAMPLING METHOD, AND ANALYSES ................................................. 3 3.5 RESOURCES AND RESERVES ....................................................................................... 3 3.6 DEVELOPMENT AND OPERATIONS ........................................................................... 5 3.6.1 Mining Operation ................................................................................................... 5 3.6.2 Processing and Smelter .......................................................................................... 5 3.7 ENVIRONMENTAL COMPLIANCE AND RECLAMATION ....................................... 6 3.8 CONCLUSIONS AND RECOMMENDATIONS ............................................................. 7 4.0 INTRODUCTION ........................................................................................................................... 8 4.1 PERSONNEL INVOLVED AND QUALIFICATIONS .................................................... 8 4.2 SITE EXAMINATIONS .................................................................................................... 9 4.3 UNITS AND DEFINITIONS ............................................................................................. 9 5.0 RELIANCE ON OTHER EXPERTS ............................................................................................ 10 6.0 PROPERTY DESCRIPTIONS AND LOCATIONS ..................................................................... 11 7.0 ACCESSIBILITY, CLIMATE, LOCAL RESOURCES, INFRASTRUCTURE AND PHYSIOGRAPHY ............................................................................................................... 13 8.0 HISTORY ...................................................................................................................................... 15 9.0 GEOLOGICAL SETTING ............................................................................................................ 16 9.1 THE J-M REEF ................................................................................................................ 16 9.2 STRUCTURAL GEOLOGY ............................................................................................ 17 9.2.1 Cross Faults ......................................................................................................... 19 9.2.2 Intrusions ............................................................................................................. 19 10.0 DEPOSIT TYPES .......................................................................................................................... 20 11.0 MINERALIZATION ..................................................................................................................... 21 11.1 LARGE-SCALE REGULARITY OF THE J-M REEF .................................................... 21 12.0 EXPLORATION ........................................................................................................................... 23 13.0 DRILLING ..................................................................................................................................... 24 14.0 SAMPLING METHOD AND APPROACH ................................................................................. 26 14.1 COMMENTS ON SMC’S QUALITY ASSURANCE/QUALITY CONTROL (QA/QC) PROCEDURES ............................................................................. 26 15.0 SAMPLE PREPARATION, ANALYSES, AND SECURITY ..................................................... 29 16.0 DATA VERIFICATION ............................................................................................................... 30 16.1 DRILLING........................................................................................................................ 30 16.2 SAMPLING AND ANALYSIS ........................................................................................ 30 17.0 ADJACENT PROPERTIES .......................................................................................................... 31 18.0 MINERAL PROCESSING AND METALLURGICAL TESTING .............................................. 32 18.1 STILLWATER CONCENTRATOR ................................................................................ 32 18.1.1 Stillwater Primary Crushing ................................................................................ 32 18.1.2 Stillwater Grinding Circuit .................................................................................. 32 18.1.3 Stillwater Flotation Circuit .................................................................................. 32 18.1.4 Stillwater Tailings ................................................................................................ 33 Project 11-030 i BEHRE DOLBEAR Technical Report for the Mining Operations at Stillwater Mining Company March 2011 TABLE OF CONTENTS (CONTINUED) 18.2 EAST BOULDER CONCENTRATOR ........................................................................... 34 18.2.1 East Boulder Grinding Circuit ............................................................................. 35 18.2.2 East Boulder Flotation Circuit ............................................................................. 35 18.2.3 East Boulder Tailings ........................................................................................... 35 18.3 COLUMBUS METALLURGICAL OPERATION .......................................................... 37 18.3.1 SMC’s Smelter ..................................................................................................... 37 18.3.2 SMC’s Base Metal Refinery ................................................................................ 37 18.3.3 SMC’s Catalyst Recycle Facility ......................................................................... 38 19.0 MINERAL RESOURCE AND MINERAL RESERVE ESTIMATES ......................................... 39 19.1 DRILL SECTION INTERPRETATIONS AND WIREFRAME CONSTRUCTION ............................................................................................................ 39 19.2 BLOCK MODELING ....................................................................................................... 39 19.3 GRADE ESTIMATION – EAST BOULDER MINE ...................................................... 40 19.4 GRADE ESTIMATION – STILLWATER MINE ........................................................... 41 19.5 RESOURCE/RESERVE DEFINITIONS ......................................................................... 42 19.6 SMC’S MINERAL RESOURCE ESTIMATES .............................................................. 43 19.7 SMC’S PROVEN AND PROBABLE MINERAL RESERVE ESTIMATES ................. 44 19.8 MINE LIFE ....................................................................................................................... 48 20.0 OTHER RELEVANT DATA AND INFORMATION ................................................................. 49 21.0 INTERPRETATION AND CONCLUSIONS ............................................................................... 50 22.0 RECOMMENDATIONS ............................................................................................................... 51 23.0 REFERENCES .............................................................................................................................. 52 24.0 DATE AND SIGNATURE PAGE ................................................................................................ 53 Richard L. Bullock ............................................................................................................ 58 25.0 ADDITIONAL REQUIREMENTS FOR TECHNICAL REPORTS ON DEVELOPMENT PROPERTIES AND PRODUCTION PROPERTIES ..................................... 62 25.1 MINING............................................................................................................................ 62 25.1.1 Stillwater and East Boulder Mining Methods ...................................................... 62 25.1.2 Stillwater Mine Operation ................................................................................... 67 25.1.3 The Major Stillwater Mine Off-shaft Deep Mine Development .......................... 68 25.1.4 Normal Stillwater Mine Operations ..................................................................... 72 25.1.5 Stillwater Mine Production .................................................................................