Orosur Mining Regulatory News (OMI)

1 Sep 2010 07:00

Orosur Mining Inc. ('OMI' or 'the Company') (TSX-V: OMI) (AIM: OMI), a South American-focused gold producer and explorer, announces the results of the first NI 43-101-compliant resource for the Pantanillo Norte deposit in Chile.

David Fowler, CEO of the Company commented: "This initial Independent NI 43-101 Mineral resource estimate for our Pantanillo project is a critical step in our objective to create a second producing asset for the Company in Chile. The 2010 drill programme at Pantanillo targeted the oxidized and mixed portion of the deposit and has confirmed total measured and indicated resources of 47,093,000 tonnes at a grade of .69 g/t gold, for 1,049,071 ounces of gold. Outside of this initial resource, OMI intends to evaluate the deeper sulphide mineralisation which we believe represents a significant exploration target. This work will be undertaken as part of the scoping studies which are ongoing and follow-up drilling".

Background

The Pantanillo property covers 11,750 hectares and is located approximately 125 km east of Copiapo in the Maricunga Belt in northern Chile. The Maricunga Belt hosts approximately 60 million gold-equivalent ounces of known resources with two projects in production (Maricunga, La Coipa - formerly known as Refugio) and at least five other projects undergoing feasibility and advanced exploration work (Caspiche, Cerro Casale, Lobo Marte, El Morro and La Pepa). The Pantanillo Norte deposit is a gold porphyry system similar to others in the Maricunga District, and the bulk of the mineralization within the deposit consists of sheeted quartz/sulphide /±magnetite vein swarms and minor stockwork veining and intrusive breccias hosted in andesite porphyry of high-level intrusive origin.

NI 43-101 Mineral Resource

Some 14,900 meters of historical drilling on the Pantanillo Norte deposit by Anglo American and Kinross has been followed by a further 5,600 meters drilled during the 2010 field season by OMI. The combined work has resulted in this first NI 43-101 mineral resource for the Pantanillo Norte deposit. Drilling and development work on the Pantanillo deposit is being performed in a phased approach. The first phase, completed during the 2010 drill season, focused on defining the oxide and mixed zones of the deposit for which higher metallurgical recoveries are expected using conventional heap leach processing.

Total Measured and Indicated mineral resources are 47,093,000 tonnes at 0.69 g/t gold, for 1,049,071 ounces of gold, with a further 304,000 tonnes at 0.53 g/t gold, for 5,166 ounces of gold, in the Inferred category. The following table gives a breakdown by category of the resource estimated by AMEC International Ingeniería y Construcción Limitada.

The resource estimate utilized ordinary kriging for grade interpolation. To ensure reasonable prospects of economic extraction in open pit operations, mineral resources are reported within a Lerchs-Grossman (LG)-optimized pit shell using Whittle® software with the following parameters: gold price of 1,035 US$/oz; mining cost of 1.65 US$/t; processing cost of 4.0 US$/t; general and administration cost of 1.0 US$/t, and recoveries of 75% for leached and oxide ore types, 65% for mixed ore, and 50% for sulphide ore. The resource estimate was completed by Paula Larrondo, MAusIMM, Principal Geostatistician with AMEC International Ingeniería y Construcción Limitada. The effective date of the estimation is July 9th, 2010.

Higher-grade mineralization distribution is well constrained in space within the deposit and resulted in the objective definition of volume and grade

The resource estimate is based on a total of 78 holes and 20,530 meters of drilling, including 27 Anglo American and 21 Kinross historic holes (17 DDH, 30 RC, and 1RC/DDH) drilled between 1988 and 2008, for a total of 14,892 meters, and 30 holes drilled by Orosur in 2010, which include 19 DDH and 11RC for a total of 5,638 meters.

Next Steps

A second phase of metallurgical test work and drilling is planned to evaluate the deeper sulphide mineralization, which is assumed to have lower recoveries and potentially may require alternative processing methods. Outside of the resource described above, there is a target for further exploration of approximately 30 to 40 million tonnes at a grade of between 0.8 to 0.6 g/t Au of predominantly sulphide mineralization. At this point in time, the potential tonnes and grade of the exploration target is conceptual in nature, there has been insufficient exploration to define this target as a mineral resource, and it is uncertain if further exploration will result in the target being delineated as a mineral resource.

Only limited drilling has been conducted below the optimised pit and there remains potential to expand sulphide mineralisation and ultimately significantly increase resources. One section has historically been drilled to 700 meters down hole depth with one hole intersecting 138 meters at 0.75 g/t Au from 562 meters down hole. Two cross sections illustrating this additional sulphide potential have been provided on the company's website at the following link: http://www.orosur.ca/exploration_chile/pantanillo/

Work on the scoping study for Pantanillo commenced in June 2010. Key aspects to be assessed will be the metallurgical characteristics, environmental studies and water and infrastructure requirements. A comprehensive metallurgical test program is planned for completion early in 2011. Base-line environmental studies will commence when site access is again available between September and October 2010, and will be followed by geotechnical and hydrological studies during the summer months in the Southern hemisphere. Prefeasibility studies are planned to commence during 2011. The Company's objective at Pantanillo is to create a second production asset for the Company in Chile.

Qualified Person's Statement

The information presented in this press release has been reviewed by William F. Lindqvist, a director of OMI. Dr. Lindqvist holds a Ph.D. in Applied Geology from Imperial College, London, has been a member of the AusIMM for 46 years, and has had 40 years of experience in international minerals exploration and property evaluation.

Forward-Looking Statements

All statements, other than statements of historical fact, contained or incorporated by reference in this news release, including any information as to the future financial or operating performance of the Company, constitute "forward-looking statements" within the meaning of certain securities laws, including the "safe harbour" provisions of the Securities Act (Ontario) and the United States Private Securities Litigation Reform Act of 1995 and are based on expectations estimates and projections as of the date of this news release. There can be no assurance that such statements will prove to be accurate; such statements are subject to significant risks and uncertainties, and actual results and future events could differ materially from those anticipated in such statements. Forward-looking statements include, without limitation success of exploration activities; permitting time lines; the failure of plant; equipment or processes to operate as anticipated; accidents; labour disputes; requirements for additional capital title disputes or claims and limitations on insurance coverage. The Company disclaims any intention or obligation to update or revise any forward-looking statements whether as a result of new information, future events and such forward-looking statements, except to the extent required by applicable law.

ENDS

Neither TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release.

About Orosur Mining Inc.

Orosur Mining Inc. is a fully integrated gold producer and exploration company focused on identifying and developing gold projects in Latin America. The Company operates the only producing gold mine in Uruguay (San Gregorio), and has assembled an exploration portfolio of high quality assets in Uruguay and Chile. The Company is quoted in Canada (TSX-Venture Exchange: OMI) and London (AIM: OMI).

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