Orosur Mining Inc Announces Drill Results for the Mahoma Project, Uruguay

SANTIAGO, Chile--(BUSINESS WIRE)--Orosur Mining Inc. (“OMI” or “the Company”) (TSX VENTURE: OMI) (LSE: OMI), a South American-focused gold producer and explorer, today announces drill results from its 100 per cent owned Mahoma Project in Uruguay. The drilling programme is designed to confirm grades and widths found historically at Mahoma.

• Current drilling campaign confirms similar narrow high grade gold results on Veta II as per historical drilling.
• Drill program to be expanded to target the definition of a NI 43-101 compliant resource during calendar 2012 with the goal of providing the basis for a feasibility study to target annual mine production of 25,000 ounces of gold that could be processed at the San Gregorio mine.

David Fowler, CEO of the Company, stated, "We are pleased with drill results from our first pass drill program at Mahoma as they have confirmed historically identified grades and widths on Veta II. Orosur will now expand its drilling programme with the objective of defining a resource during calendar 2012. It is anticipated that this resource will provide the basis for a feasibility study to produce a total of 25,000 ounces per annum. The study will be based on ore being transported to the San Gregorio mine to minimise capital expenditure and reduce study and permitting time."

The Company has completed 24 drill holes for 1,815 meters from an initial planned drill programme of approximately 3,000 meters, comprising 2,000 metres of RC pre-collars and 1,000 metres of diamond drilling. The drill programme is designed to generally confirm historical drill results for vein I, vein II and vein IIB. This work is expected to be followed by infill drilling to target an initial measured and indicated resource of 250,000 tonnes.

Table 1. Drill-Hole Results for the Mahoma Project, Uruguay
Target	Drill Hole No	From	To	Interval	Interval g/t Au
VETA II ESTE	MHDD001	No significant results
VETA II ESTE	MHDD002	No significant results
VETA II ESTE	MHDD003	42.30	42.75	0.45	21.86
		60.75	61.15	0.40	14.38
VETA II ESTE	MHDD004	No significant results
VETA II ESTE	MHDD005	85.40	85.70	0.30	56.17
		85.70	86.03	0.33	1.40
		87.53	88.25	0.72	2.00
VETA II ESTE	MHDD006	84.95	85.50	0.55	5.33
		86.70	87.20	0.50	2.45
		88.30	88.62	0.32	46.60
		88.62	88.93	0.31	29.30
		88.93	89.43	0.50	1.13
VETA II ESTE	MHDD007	82.55	82.95	0.40	7.97
		85.55	86.60	1.05	2.83
VETA II ESTE	MHDD008	80.45	80.90	0.45	3.47
VETA II ESTE	MHDD009	71.30	71.75	0.45	41.05
		72.20	72.60	.40	5.67
		73.00	73.50	0.50	3.43
		73.80	74.20	0.40	100.63
		74.60	75.00	0.40	6.10
		75.00	75.40	0.40	3.16
		81.30	81.80	0.50	3.11
VETA II ESTE	MHDD010	83.95	84.35	0.40	5.30
		85.85	86.30	0.45	3.46
VETA II ESTE	MHDD015	83.90	84.40	0.50	19.57
		84.40	85.15	0.75	4.79
		86.65	87.15	0.50	12.23
VETA II ESTE	MHRC001	28.00	29.00	1.00	10.86
		43.00	44.00	1.00	15.20
VETA II ESTE	MHRC002	6.00	7.00	1.00	2.10
VETA II ESTE	MHRC003	No significant results
VETA II OESTE	MHDD022	No significant results
VETA II OESTE	MHDD023	No significant results
VETA II OESTE	MHDD025	57.80	58.30	0.50	2.67
VETA II OESTE	MHRC008	No significant results
VETA II OESTE	MHRC009	No significant results
VETA II OESTE	MHRC010	42.00	43.00	1.00	4.25
		43.00	44.00	1.00	14.13
		44.00	45.00	1.00	2.13
VETA IIB	MHDD018	No significant results
VETA IIB	MHDD019	No significant results
VETA IIB	MHRC004	No significant results
VETA IIB	MHRC005	No significant results

A drill hole plan map and sections are available on the Company’s website.

Diamond drill holes 1 to 10 and 15 and reverse circulation drill holes 1 to 3 were all drilled within the historically defined 600 meter main portion of the II vein. Diamond drill holes 1 and 2 confirm previous drilling that showed no significant mineralisation on the sections and to depths drilled. Short intervals were assayed to understand grade distribution. While many of the intercepts are narrow the current drilling supports the envisaged target of 9-10 g/t Au over a minable width of 1.5 meters.

Drilling on Veta II Oeste and Veta IIB has not confirmed mineralisation identified in a number of historic sections with results less consistent than expected.

Table 2. Drill Hole Location Data, Mahoma Project, Uruguay
Drill Hole No	East_GK	North_GK	RL	Azimuth	Dip	Depth
MHRC003	401915	6219796	91.5	175	-50	40
MHRC002	402064	6219819	88	175	-55	30
MHDD015	402208	6219880	87	175	-65	110
MHDD010	402337	6219899	82	175	-60	96
MHDD009	402360	6219902	81	175	-60	89
MHDD008	402382	6219903	81	175	-60	85
MHDD007	402408	6219908	80	175	-60	91
MHDD006	402436	6219910	80	175	-60	96
MHDD005	402457	6219909	78	175	-60	93
MHDD004	402483	6219911	78	175	-60	81
MHDD003	402507	6219912	77	175	-55	66
MHRC001	402532	6219900	77	175	-60	60
MHDD002	402582	6219923	76	175	-60	110
MHDD001	402631	6219927	75	175	-50	78
MHDD025	401316	6219756	101.5	175	-55	70
MHRC008	401366	6219760	101	175	-60	70
MHDD022	401439	6219787	101	175	-50	76
MHDD023	401464	6219784	100	175	-50	68
MHRC010	401489	6219791	99	175	-50	60
MHRC009	401517	6219773	100	175	-45	70
MHRC005	401741	6219538	97	175	-45	45
MHRC004	401893	6219553	99	185	-55	70
MHDD019	402044	6219550	99	185	-55	80
MHDD018	402116	6219552	98	175	-55	79
						1,815

About Mahoma

The Project area contains four principal gold bearing quartz veins that were previously mined via shallow open pits within granodiorite host rocks. The granodiorite stock measures approximately 3 km wide in the Mahoma area and contains additional quartz veins that have not yet been explored. The area is located approximately 130 kilometres from Montevideo and 405 kilometres from the San Gregorio mine in the Florida Greenstone belt.

Four principal veins have been identified; veins I, II, IIB and IV. Vein II is the longest and most consistent that has been historically drilled and mined. It has a drilled strike length of 900 metres and a shallow open pit extends along 450 metres of its strike length. The main portion of Vein II is sub vertical and the average true thickness is around 1.7 metres. A second portion of vein II is approximately 1,200 metres to the east of the main mineralized lens and it has been drilled for over 700 metres of strike with 220 metres showing continuous mineralization. The width of the second vein varies from 0.2 metres to 3.2 metres with an average width of approximately 1.9 metres.

Vein IIB, 300 metres to the south of vein II, is approximately 550 metres in length and exhibits an average width of 1.5 metres. Vein IV is a thicker quartz vein zone than the other zones but also has a lower grade and a shorter strike length of approximately 250 metres. It has been drilled to only 30 metres from the surface. Vein I comprises a series of short and narrow veins with the average width of these veins being 20 centimetres and the largest vein having a strike length of 100 metres.

Only the upper portions of the four drill hole defined veins have previously been mined and there is significant exploration upside potential to define more veins and extend the known veins down dip.

Orosur has held the property since 2009, however, issues with land access had previously prevented exploration. During the second half of 2011 these issues were resolved and exploration is now being conducted.

The Mahoma Project, previously operated by American Resource Corporation, produced 16,419 ounces (73,431 tonnes at 6.98 g/t Au with 91.6 per cent recovery) between 1993 and 1997. A pre-mining non -compliant NI 43-101 probable reserve of 281,000 tonnes at a diluted grade of 9.36 g/t (15 per cent dilution assumed) was estimated by Watts, Griffis and McOuat.

Assaying and Qualified Person

Project geologists log and mark the core then technicians cut the individual lengths with a diamond saw, tag the sample bags and secure them with security clips. The samples are then transported to the Company’s laboratory facility at San Gregorio. They are dried and crushed to -2mm. A 1,000 gram split of the coarse material is then pulverized to -200 mesh. The rejects remained at the prep facility and the pulps are analyzed for gold by 30g fire assay with an AA/gravimetric finish. In addition, a 214 element ICP analysis is conducted on selective samples. A QA/QC program has been implemented as part of the sampling procedure for the drill program. One standard, one blank or one duplicate are inserted per group of ten samples sent to the laboratory. The information in this news release has been approved by William Lindqvist, the Company's Qualified Person under National Instrument 43-101 standards.

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).