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Press release from Marketwire

Golden Star Increases Mineral Reserves by 24%; Increases Measured and Indicated Mineral Resources by 63%

Wednesday, February 23, 2011

Golden Star Increases Mineral Reserves by 24%; Increases Measured and Indicated Mineral Resources by 63%21:52 EST Wednesday, February 23, 2011DENVER, COLORADO--(Marketwire - Feb. 23, 2011) - Golden Star Resources Ltd. (TSX:GSC)(NYSE Amex:GSS)(GSE:GSR) ("Golden Star" or the "Company") is pleased to announce significant increases in its Proven and Probable Mineral Reserves (collectively "Mineral Reserves") and Mineral Resources as at December 31, 2010. Mineral Reserves, net of mining depletion, increased by 882,000 ounces or 24% by reaching a tonnage of 65.3 million grading 2.20 grams per tonne (g/t) for contained gold of 4.62 million ounces at year end. The increase was the result of successful exploration efforts (38%) and an increased gold price (55%). The remainder of the increase (7%) was due to geologic modeling, data interpretation, resource block modeling and changes in engineering parameters. Mining depletion totaled 460,000 ounces of gold and therefore the total reserve addition before depletion was 1.35 million ounces of gold, equivalent to a 36% increase over the Mineral Reserves at December 31, 2009. Measured and Indicated Mineral Resources increased 63% over 2009 to 54.9 million tonnes grading 1.99 g/t gold. Inferred Mineral Resources increased 20% over 2009 to 16.5 million tonnes grading 3.66 g/t gold. Tom Mair, President and CEO, said, "We are very pleased to report that our focus on organic growth through exploration has delivered results in 2010. In 2011, we will increase our exploration budget by $10 million to $30 million. Approximately 80% of this 2011 budget will be spent within haul distance of our existing processing plants. This year's results demonstrate the potential of our district-scale property holdings around both mine sites." Mitchel Wasel, Vice President of Exploration added, "Based on this year's success, by mid-year, we will have nine drill rigs turning in Ghana in proximity to our processing plants. Our goal is to continue replacing and adding to our reserves and resources in the coming year. Our historical practice of using optimized pit shells for constraining resources has resulted in a high conversion of resources to reserves of approximately 70%." The Mineral Reserve and Mineral Resource estimates have been estimated by our technical personnel in accordance with definitions and guidelines set out in the Definition Standards for Mineral Resources and Mineral Reserves published by the Canadian Institute of Mining, Metallurgy, and Petroleum and as required by Canada's National Instrument 43-101. MINERAL RESERVESPROVEN & PROBABLE MINERAL RESERVESAs at December 31, 2010As at December 31, 2009Property Mineral Reserve CategoryTonnes (millions)Gold Grade (g/t)Ounces (millions)Tonnes (millions)Gold Grade (g/t)Ounces (millions)Bogoso/PresteaProven Mineral ReservesNon-refractory1.31.580.061.11.600.06Refractory12.02.791.079.73.080.96Total Proven13.22.671.1410.82.921.01Probable Mineral ReservesNon-refractory7.02.310.525.02.600.42Refractory26.92.452.1315.52.651.32Total Probable34.02.422.6520.52.641.73Total Proven and ProbableNon-refractory8.32.200.596.12.420.47Refractory38.92.563.2025.12.812.27Total Bogoso/Prestea Proven and Probable47.22.493.7831.22.742.75Wassa/HBBProven Mineral ReservesNon-refractory0.61.140.020.81.910.05Probable Mineral ReservesNon-refractory17.51.440.8116.31.790.94Total Wassa/HBB Proven and Probable18.11.430.8317.11.790.99TotalsProven Mineral ReservesNon-refractory1.91.430.091.91.730.11Refractory12.02.791.079.73.080.96Total Proven13.92.601.1611.62.861.06Probable Mineral ReservesNon-refractory24.51.691.3321.31.981.35Refractory26.92.452.1315.52.651.32Total Probable51.52.093.4636.82.262.67Total Proven and ProbableNon-refractory26.41.671.4223.21.961.46Refractory38.92.563.2025.12.812.27Total Proven and Probable65.32.204.6248.32.403.73(1)The stated Mineral Reserve for Bogoso/Prestea includes Prestea South, Pampe and Mampon.(2)The stated Mineral Reserve for Wassa/HBB includes the Hwini-Butre and Benso properties.(3)The stated Mineral Reserves have been prepared in accordance with Canada's National Instrument 43-101 Standards of Disclosure for Mineral Projects and are classified in accordance with the Canadian Institute of Mining, Metallurgy and Petroleum's "CIM Definition Standards – For Mineral Resources and Mineral Reserves". Mineral Reserves are equivalent to "proven" and "probable reserves" as defined by the SEC Industry Guide 7. Mineral Reserve estimates reflect the Company's reasonable expectation that all necessary permits and approvals will be obtained and maintained. Mining dilution and mining recovery vary by deposit and have been applied in estimating the Mineral Reserves. (4)The 2010 and 2009 Mineral Reserves were prepared under the supervision of Mr. Karl Smith, Vice President Technical Services for the Company. Mr. Smith is a "Qualified Person" as defined by Canada's National Instrument 43-101.(5)The Mineral Reserves at December 31, 2010 were estimated using a gold price of $1,025 per ounce, which is approximately equal to the three-year average gold price. At December 31, 2009, Mineral Reserves were estimated using a gold price of $850 per ounce.(6)The terms "non-refractory" and "refractory" refer to the metallurgical characteristics of the ore and are defined in the Glossary of Terms. We plan to process the refractory ore in our sulfide bio-oxidation plant at Bogoso and to process the non-refractory ore using our more traditional gravity, flotation and/or cyanidation techniques.(7)The slope angles of all pit designs are based on geotechnical criteria as established by external consultants. The size and shape of the pit designs are guided by consideration of the results from a pit optimization program which incorporates historical and projected operating costs at Bogoso/Prestea, Wassa and Hwini-Butre and Benso. Metallurgical recoveries are based on historical performance or estimated from test work and typically range from 80% to 95% for non-refractory ores and from 70% to 85% for refractory ores. A government royalty of 5% of gold revenues is allowed as are other applicable royalties. (8)Numbers may not add due to rounding.Reconciliation of Mineral ReservesContainedTonnesOunces Tonnes (millions)Ounces (millions)(% of Opening)(% of Opening)Mineral Reserves at December 31, 200948.33.73100%100%Gold price increase (1 and 6)15.50.7432%20%Exploration changes (2 and 7)4.30.519%14%Mining depletion (3)(4.3) (0.46) -9%-12%Engineering (4)1.50.103%3%Mineral Reserves at December 31, 2010 (5)65.34.62135%124%Notes to the reconciliation of Mineral Reserves:(1)Gold Price Increase represents changes resulting from an increase in gold price used in the Mineral Reserve estimates from $850 per ounce in 2009 to $1,025 per ounce in 2010.(2)Exploration Changes include changes due to geological modeling, data interpretation and resource block modeling methodology as well as exploration discovery of new mineralization. (3)Mining Depletion represents the 2009 Mineral Reserve within the volume mined in 2010 with adjustments to account for stockpile addition and depletions during 2010 and therefore does not correspond with 2010 actual gold production.(4)Engineering includes changes as a result of engineering facts such as changes in operating costs, mining dilution and recovery assumptions, metallurgical recoveries, pit slope angles and other mine design and permitting considerations.(5)Numbers may not add due to rounding.(6)Pit design changes that are primarily due to a higher gold price are included here.(7)Pit design changes that are primarily due to exploration discoveries are included here.NON-RESERVE—MEASURED AND INDICATED MINERAL RESOURCESCautionary Note to US Investors concerning estimates of Measured and Indicated Mineral ResourcesThis section uses the terms "Measured Mineral Resources" and "Indicated Mineral Resources". We advise US investors that while these terms are recognized and required by Canadian regulations, the US Securities and Exchange Commission does not recognize them. US investors are cautioned not to assume that any part or all of the mineral deposits in these categories will ever be converted into mineral reserves.Our Measured and Indicated Mineral Resources reported below are exclusive of the Proven and Probable Mineral Reserves as shown above and have been estimated in compliance with definitions set out in Canada's National Instrument 43-101.Except as otherwise provided, the total Measured and Indicated Mineral Resources for all properties have been estimated at an economic cut-off grade based on a gold price of $1,300 per ounce for December 31, 2010 and $1,000 per ounce for December 31, 2009 and on economic parameters deemed realistic. The economic cut-off grades for Mineral Resources are lower than those for Mineral Reserves and are indicative of the fact that the Mineral Resource estimates include material that may become economic under more favorable conditions including increases in gold price.The following table summarizes our estimated non-reserves – Measured and Indicated Mineral Resources as of December 31, 2010 as compared to the totals for December 31, 2009:MeasuredIndicatedMeasured & IndicatedGoldGoldGoldTonnesGradeTonnesGradeTonnesGradeProperty(millions)(g/t)(millions)(g/t)(millions)(g/t)Bogoso/Prestea (1)8.51.9419.32.0027.81.98Prestea Underground--1.115.801.115.80Wassa0.10.8820.31.0720.41.07Benso--0.82.530.82.53Chichiwelli Manso--0.91.800.91.80Hwini-Butre--0.52.070.52.07Father Brown Underground (8)--0.86.680.86.68Goulagou (7)--2.71.752.71.75Total 20108.61.9346.42.0054.91.99Total 20094.81.8721.82.6626.62.52Notes to Non-Reserves-Measured & Indicated Mineral Resources: (1)The Mineral Resources for Bogoso/Prestea include Pampe and Mampon. (2)The Mineral Resources were estimated in accordance with the definitions and requirements of Canada's National Instrument 43-101. The Mineral Resources are equivalent to Mineralized Material as defined by the SEC Industry Guide 7. (3)The Mineral Resources, other than for Goulagou (see Note 8), were estimated using optimized pit shells at a gold price of $1,300 per ounce from which the Mineral Reserves have been subtracted. Other than gold price, the same optimized pit shell parameters and modifying factors used to determine the Mineral Reserves were used to determine the Mineral Resources. The Prestea Underground resource was estimated using a $1,300 per ounce gold price and operating cost estimates. In 2009, we used a gold price of $1,000 per ounce for the optimized shell. (4)The Mineral Resources are not included in and are in addition to the Mineral Reserves described above. (5)The Qualified Person for the estimation of the Mineral Resources is S. Mitchel Wasel, Golden Star Resources Vice President of Exploration. (6)Numbers may not add due to rounding. (7)The Mineral Resources for Goulagou were estimated using optimized pit shells at a gold price of $560. Pit optimization parameters for the Goulagou Mineral Resources were estimated based on feasibility studies on other similar gold deposits in Burkina Faso, Golden Star's experience in West Africa, and from limited metallurgical test work on the Goulagou ores. Heap leach processing was the assumed processing option for this deposit. Goulagou is 10% owned by an unrelated party. (8)The Father Brown Underground resource has been estimated below the $1,300 pit shell down to the 700 m elevation using an economic gold grade cut off of 4.5 g/t. NON-RESERVES – INFERRED MINERAL RESOURCESCautionary Note to US Investors concerning estimates of Inferred Mineral ResourcesThis section uses the term "Inferred Mineral Resources." We advise US investors that while this term is recognized and required by NI 43-101, the US Securities and Exchange Commission does not recognize it. "Inferred Mineral Resources" have a great amount of uncertainty as to their existence, and great uncertainty as to their economic and legal feasibility. It cannot be assumed that all or any part of Inferred Mineral Resources will ever be upgraded to a higher category. In accordance with Canadian rules, estimates of Inferred Mineral Resources cannot form the basis of feasibility or other economic studies. US investors are cautioned not to assume that any part or all of the Inferred Mineral Resource exists, or is economically or legally mineable.Our Inferred Mineral Resources have been estimated in compliance with definitions defined by NI 43-101.TonnesGold GradeProperty(M)(g/t)Bogoso/Prestea (1)10.62.11Prestea Underground 4.1 8.2Wassa0.12.27Benso0.13.56Chichiwelli Manso 0.71.71Hwini-Butre 0.12.23Father Brown Underground (8) 0.4 5.97Goulagou (7)0.51Total 201016.53.66Total 200911.04.62Notes to Non-Reserves—Inferred Mineral Resources(1) The Inferred Mineral Resources for Bogoso/Prestea incorporates Pampe and Mampon. (2) The Inferred Mineral Resources were estimated in accordance with the definitions and requirements of Canada's National Instrument 43-101. Inferred Mineral Resources are not recognized by the United States Securities and Exchange Commission. (3) The Inferred Mineral Resources, other than for Goulagou, were estimated using an optimized pit shell at a gold price of $1,300 per ounce from which the Mineral Reserves have been subtracted. Other than gold price, the same optimized pit shell parameters and modifying factors used to determine the Mineral Reserves were used to determine the Mineral Resources. For Goulagou, optimized pit shell at a gold price of $560 per ounce was used. The Prestea Underground resource was estimated using an $1,300 per ounce gold price and operating cost estimates.(4) The Inferred Mineral Resources are not included in and are in addition to the Mineral Reserves described above. (5) The Qualified Person for the estimation of the Inferred Mineral Resources is S. Mitchel Wasel, Golden Star Resources Vice President of Exploration. (6) Numbers may not add due to rounding. (7) Pit optimization parameters for the Goulagou Inferred Mineral Resources were estimated based on feasibility studies on other similar gold deposits in Burkina Faso, Golden Star's experience in West Africa, and from limited metallurgical test work on the Goulagou ores. Heap leach processing was the assumed processing option for this deposit. (8) The Father Brown Underground resource has been estimated below the $1,300 pit shell down to the 700 m level elevation using an economic gold grade cut-off of 4.5 g/t.COMPANY PROFILEGolden Star holds a 90% equity interest in Golden Star (Bogoso/Prestea) Limited and Golden Star (Wassa) Limited, which respectively own the Bogoso/Prestea and Wassa/HBB open-pit gold mines in Ghana. In addition, Golden Star has an 81% interest in the currently inactive Prestea Underground mine in Ghana, as well as gold exploration interests elsewhere in Ghana, in other parts of West Africa and in Brazil in South America. Golden Star has approximately 258 million shares outstanding.Statements Regarding Forward-Looking Information: Some statements contained in this news release are forward- looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Such statements include our expectations regarding reserves and resources increases for 2011, our 2011 exploration activities and the number of drill rigs conducting such exploration, and our plans for processing refractory ore and non-refractory ore. Investors are cautioned that forward-looking statements are inherently uncertain and involve risks and uncertainties that could cause actual facts to differ materially. There can be no assurance that future developments affecting the Company will be those anticipated by management. Please refer to the discussion of these and other factors in our Form 10-K for 2009. The forecasts contained in this press release constitute management's current estimates, as of the date of this press release, with respect to the matters covered thereby. We expect that these estimates will change as new information is received. While we may elect to update these estimates at any time, we do not undertake any estimate at any particular time or in response to any particular event.FOR FURTHER INFORMATION PLEASE CONTACT: Bruce Higson-SmithGolden Star Resources Ltd.Vice President Corporate Development+1-800-553-8436ORAnne HiteGolden Star Resources Ltd.Investor Relations Manager+1-800-553-8436www.gsr.com