SAN DIMAS PROPERTY SAN DIMAS DISTRICT DURANGO AND SINALOA STATES, MEXICO TECHNICAL REPORT Prepared by: Primero Mining Corp. and AMC Mining Consultants (Canada) Ltd. In accordance with the requirements of National Instrument 43-101, “Standards of Disclosure for Mineral Projects”, of the Canadian Securities Administrators Qualified Persons: Gabriel Voicu, P.Geo J M Shannon, P. Geo. R Webster, M.AIG April 18, 2014 San Dimas Technical Report CONTENTS 1 SUMMARY 8 2 INTRODUCTION 18 2.1 General and Terms of Reference ......................................................... 18 2.2 The Issuer ........................................................................................... 18 2.3 Report Authors ................................................................................... 19 3 RELIANCE ON OTHER EXPERTS 22 4 PROPERTY DESCRIPTION AND LOCATION 22 4.1 Property Location ............................................................................... 22 4.2 Property Description and Ownership ................................................... 22 4.3 Land Tenure ....................................................................................... 23 4.4 Surface Rights and Permits ................................................................. 25 4.5 Existing Environmental Liabilities ...................................................... 25 5 ACCESSIBILITY, CLIMATE, LOCAL RESOURCES, INFRASTRUCTURE AND PHYSIOGRAPHY 26 5.1 Accessibility ....................................................................................... 26 5.2 Climate ............................................................................................... 26 5.3 Local Resources and Infrastructure ..................................................... 27 5.4 Physiography and Vegetation .............................................................. 28 6 HISTORY 29 6.1 Ownership .......................................................................................... 29 6.2 Exploration Work ............................................................................... 30 6.3 Historical Estimates ............................................................................ 30 6.4 Production .......................................................................................... 31 7 GEOLOGICAL SETTING AND MINERALIZATION 31 7.1 Regional Geology ............................................................................... 31 7.2 Local and Property Geology................................................................ 33 7.3 Mineralization .................................................................................... 34 8 DEPOSIT TYPES 36 8.1 General ............................................................................................... 36 8.2 San Dimas .......................................................................................... 37 9 EXPLORATION 37 9.1 Introduction ........................................................................................ 37 9.2 Channel Sampling ............................................................................... 37 10 DRILLING 40 10.1 Introduction ........................................................................................ 40 10.2 Exploration Drilling in 2013 ............................................................... 41 10.2.1 Central Block ....................................................................................... 42 10.2.2 Sinaloa Graben .................................................................................... 42 10.2.3 Arana Hanging Wall – Tayoltita .......................................................... 43 10.2.4 Arana Hanging Wall – Santa Rita ........................................................ 43 10.3 Sampling ............................................................................................ 43 10.4 Bulk Density ....................................................................................... 45 11 SAMPLE PREPARATION, ANALYSES AND SECURITY 46 April 2014 2 San Dimas Technical Report 11.1 Introduction ........................................................................................ 46 11.2 Sample Handling and Preparation ....................................................... 46 11.3 Sample Analysis ................................................................................. 46 11.4 Data Security ...................................................................................... 47 11.5 Laboratory Audit ................................................................................ 47 11.6 Assay QA / QC ................................................................................... 47 12 DATA VERIFICATION 57 12.1 Introduction ........................................................................................ 57 12.2 Data Transfer ...................................................................................... 57 12.2.1 Assay Integrity .................................................................................... 57 12.2.2 Data Flow ............................................................................................ 58 12.3 Mill Reconciliation ............................................................................. 59 12.4 Model Depletion ................................................................................. 60 12.5 Production Comparison....................................................................... 60 12.6 Exploration Data ................................................................................. 61 12.7 Conclusion ......................................................................................... 62 13 MINERAL PROCESSING AND METALLURGICAL TESTING 62 14 MINERAL RESOURCE ESTIMATES 63 14.1 Background ........................................................................................ 63 14.2 Block Model Estimates ....................................................................... 63 14.2.1 Introduction ......................................................................................... 63 14.2.2 Data Provided ...................................................................................... 65 14.2.3 Vein Modelling Method ....................................................................... 67 14.2.4 Samples ............................................................................................... 68 14.2.5 Bulk Density ........................................................................................ 68 14.2.6 Statistics and Compositing ................................................................... 69 14.2.7 Block Modelling .................................................................................. 75 14.2.8 Resource Classification of Block Models ............................................. 77 14.2.9 Results of Block Model Estimation ...................................................... 78 14.3 Polygonal Estimates ............................................................................ 81 14.3.1 History of Polygonal Estimates ............................................................ 81 14.3.2 AMC Review ....................................................................................... 82 14.3.3 Calculation of Tonnage ........................................................................ 83 14.3.4 Results of Review of Polygons ............................................................. 83 14.4 Mineral Resource Estimate ................................................................. 84 14.5 Comparison Year End-2012 and Year End-2013 Mineral Resources ... 84 14.5.1 Exploration Potential ........................................................................... 85 15 MINERAL RESERVE ESTIMATES 86 15.1 Introduction ........................................................................................ 86 15.2 Methodology ...................................................................................... 86 15.3 Mining Cut-off Grade ......................................................................... 86 15.4 Dilution and Mining Recovery Factors ................................................ 87 15.4.1 Dilution ............................................................................................... 87 15.4.2 Mining Recovery Factors ..................................................................... 88 15.5 Mineral Reserves Estimate .................................................................. 89 15.5.1 Mineral Reserves Statement ................................................................. 89 15.5.2 Breakdown of Mineral Reserves by Vein ............................................. 89 15.5.3 Conversion of Indicated Resources to Reserves .................................... 90 April 2014 3 San Dimas Technical Report 15.5.4 Reserve Sensitivity .............................................................................. 91 15.6 Comparison Year End-2012 and Year End-2013 Mineral Reserves ..... 91 15.7 Discussion on 2013 Production and Estimated Mineral Reserves ......... 91 16 MINING METHODS 92 16.1 General Description ............................................................................ 92 16.2 San Dimas Production & Costs ........................................................... 93 16.2.1 Production ........................................................................................... 93 16.2.2 Operating Costs ................................................................................... 94 16.3 Mining Methods & Mine Design