NI 43-101 Technical Report on Resources and Reserves, Golden Star Resources, Bogoso/Prestea Gold Mine, Ghana Effective Date: December 31, 2017 Golden Star Resources Ltd. 150 King Street West Suite 1200 Toronto ON, M5H 1J9, Canada Qualified Persons Martin Raffield, P.Eng Mitch Wasel, MAusIMM (CP) March 2018 NI 43-101 Technical Report on Resources and Reserves, Golden Star Resources, Bogoso/Prestea Gold Mine Page ii Table of Contents 1 Executive Summary................................................................................................ 1 1.1 Introduction ..........................................................................................................................1 1.2 Property Description and Ownership ...................................................................................1 1.3 Geology and Mineralization ................................................................................................2 1.4 Exploration Status ................................................................................................................2 1.5 Mineral Resources ...............................................................................................................2 1.6 Mineral Reserves .................................................................................................................3 1.7 Mining Method ....................................................................................................................4 1.8 Recovery Methods ...............................................................................................................5 1.9 Infrastructure ........................................................................................................................6 1.10 Market Studies and Contracts ..............................................................................................7 1.11 Social and Environmental Aspects ......................................................................................7 1.12 Capital and Operating Costs ................................................................................................9 1.13 Economic Analysis ..............................................................................................................9 2 Introduction .......................................................................................................... 10 2.1 Scope of Technical Report .................................................................................................10 2.2 Qualified Persons ...............................................................................................................10 2.3 Site Visits ...........................................................................................................................10 3 Reliance on Other Experts ................................................................................... 11 4 Property Description and Location .................................................................... 12 4.1 Location of Mineral Concessions ......................................................................................12 4.2 Mineral Titles and Agreements ..........................................................................................16 4.3 Surface Rights ....................................................................................................................16 4.4 Royalties and Encumbrances .............................................................................................17 4.5 Historic Environmental Liability and Indemnity ...............................................................17 4.6 Permits and Authorization .................................................................................................18 5 Accessibility, Climate, Local Resources, Infrastructure and Physiography .. 19 5.1 Accessibility .......................................................................................................................19 5.2 Physiography and Vegetation ............................................................................................19 5.3 Land Use and Proximity to Local Population Centres .......................................................19 5.4 Local Resources and Infrastructure ...................................................................................20 5.5 Climate and Length of Operating Season ..........................................................................20 6 History ................................................................................................................... 21 6.1 Prior Ownership .................................................................................................................21 6.2 Past Exploration and Development ....................................................................................22 6.3 Historic Mineral Resource and Reserve Estimates ............................................................23 6.4 Historic Mine Production ...................................................................................................24 7 Geological Setting and Mineralization ............................................................... 27 7.1 Regional Geology ..............................................................................................................27 7.2 Local Geology and Mineralization ....................................................................................30 March 2018 NI 43-101 Technical Report on Resources and Reserves, Golden Star Resources, Bogoso/Prestea Gold Mine Page iii 8 Deposit Types ........................................................................................................ 49 9 Exploration ............................................................................................................ 52 9.1 Bogoso Prestea ...................................................................................................................52 9.2 Mampon-Abronye ..............................................................................................................53 9.3 Prestea Underground ..........................................................................................................54 10 Drilling ................................................................................................................... 61 10.1 Open Pit .............................................................................................................................61 10.2 Prestea Underground ..........................................................................................................65 11 Sample Preparation, Analyses and Security ...................................................... 72 12 Data Verification .................................................................................................. 74 12.1 Introduction ........................................................................................................................74 12.2 Replicates ...........................................................................................................................74 12.3 Duplicates ..........................................................................................................................75 12.4 Blanks … ...........................................................................................................................80 12.5 Gannet Standards ...............................................................................................................82 12.6 Screen Fire Assay Checks ..................................................................................................86 12.7 Conclusions ........................................................................................................................87 13 Mineral Processing and Metallurgical Testing .................................................. 88 13.1 Introduction ........................................................................................................................88 13.2 2008 Testwork ...................................................................................................................88 13.3 2013 Testwork ...................................................................................................................92 13.4 2015 Testwork Program ...................................................................................................102 13.5 Predictive Metallurgy.......................................................................................................108 14 Mineral Resources .............................................................................................. 110 14.1 Open Pit ...........................................................................................................................110 14.2 Underground ....................................................................................................................128 14.3 Mineral Resource Statement ............................................................................................144 15 Mineral Reserves ................................................................................................ 145 15.1 Break-even Cut-off Grade Estimation .............................................................................145 15.2 Mine Design .....................................................................................................................145 15.3 Mineral Reserve