Re Assay Results Fierro Urco Joint Venture Project

MARIANA RESOURCES LTD AIM and PLUS code: MARL 30 October 2007 Mariana reports encouraging results from Apex Silver JV at Fierro Urco, Ecuador, with bonanza-grade gold/silver vein assays. Mariana Resources Ltd ("Mariana") is pleased to report that Apex Silver Mines Ltd ("Apex") subsidiary, Silex Ecuador SA ("Silex"), has obtained encouraging rock chip sample assay results from seven quartz veins located in the western part of the concession area. Assay results obtained by Silex include 34.5 g/t gold with 230 g/t silver over a vein width of 1.5 m. The Fierro Urco copper/gold prospect The 2,350 Ha Fierro Urco property, located 35 km NNW of Loja, comprises a large mineralized hydrothermal system with the upper parts dominated by a rhyolite/dacite intrusive complex displaying intense quartz-alunite and structurally controlled vuggy silica alteration, characteristically found in high-sulphidation gold deposits. The main exploration work conducted on the property since its discovery by the UN in 1970 included a 23 hole diamond drill programme totalling 4,578 m conducted by Newmont in the mid 1990's and an 11-hole diamond drill programme totalling 2,137m conducted by Prospection Panama SA in 1991. The more significant Newmont drill intersections include 147m @ 0.54 g/t gold, including an interval of 62m @ 0.3% copper in hole FU 1, and 46m @ 0.83 g/t gold and 0.62% copper in hole FU 2. Silex exploration program and first assay results Silex commenced preliminary field work on the property in July 2007, focusing on a 1.5km2 area located in the western part of the concession, in which quartz-sulphide veining and silicified structures have been identified. This area is located approximately 1.5km north east of the previously drilled site. Several old mine workings, believed to date from the mid-20th century, or possibly earlier, were located and rehabilitated to facilitate sampling. Over 20 veins have been mapped in an apparent conjugate vein array. A total of seven veins have been sampled to date, of which the most significant are: Española Vein, where a total of 32 channel samples was taken from a 16m-long trench, 42 m of old adit, and 34 m of outcrop. Fifteen of these samples ranged from 2.3 to 34.5 g/t gold and from 26 to 230 g/t Ag. Some of the more significant results include: 1.0m @ 16.2 g/t Au and 159 g/t Ag 1.5m @ 34.5 g/t Au and 230 g/t Ag 2.0m @ 30.4 g/t Au and 110 g/t Ag 2.0m @ 17.5 g/t Au and 87 g/t Ag Veta Ancha, a quartz-tourmaline hydrothermal vein-breccia ranging in width from 1.7 to 2.4m. A total of 13 samples was taken, with the two best results giving: 2.4m @ 1.9 g/t Au and 64 g/t Ag 1.7m @ 7.5 g/t Au and 237 g/t Ag Veta Ancha Creek, a disseminated sulphide zone where 24 samples were taken with widths ranging from 0.7 to 2.6 m. The more significant results include: 2.0m @ 4.2 g/t Au and 89 g/t Ag 2.3m @ 2.9 g/t Au and 73 g/t Ag Fierro Urco Vein, where a total of 23 channel samples were taken from narrow vein structures exposed in a 32m-long adit and outcrop. Selected results obtained were: 20cm @ 9.6 g/t Au and 398 g/t Ag 20cm @ 4.4 g/t gold and 385 g/t Ag 10cm @ 15.7 g/t Au and 946 g/t Ag An updated project map is attached and is also on the website: Apex (Silex) Joint Venture Silex, under the terms of a letter of agreement signed in January 2007, and following an initial four month 'free look' period, can acquire a 70% interest in Mariana's wholly owned Fierro Urco project, by funding exploration to the value of $2M over a 4-year period. Silex is committed to spend a minimum of $200,000 within 18 months following this free look period. Silex then has the option to earn an initial 51% conditional to a minimal cumulative exploration expenditure of $700,000 over 30 months. Commenting today, Mariana's Managing Director John Sutcliffe said: "These are very encouraging results obtained in the initial exploration program on a large, under-explored, copper/gold/silver hydrothermal system. Silex has done an excellent job in locating and rehabilitating the old workings and finding new, poorly exposed veins, some of which returned bonanza-grade gold and silver values. The vein area is located well outside the area drilled by Newmont, and may represent a new centre of mineralization that has not so far been systematically explored. We look forward to further encouraging results as work continues". ON BEHALF OF THE BOARD John Sutcliffe Managing Director ADDITIONAL INFORMATION The exploration programme is being conducted by Silex Ecuador, a subsidiary of Apex Silver Mines Ltd directed by Silex Exploration Manager, Sr. Marcelo Llerena and Mr. Julio Castañeda from the Apex South America office in Lima, Peru. Samples were prepared by ALS Chemex in Quito, Ecuador, using standard industry practice. Analytical work was carried out at the ALS Chemex laboratory in Lima using conventional fire/ICP assay techniques. Exploration information in this announcement has been compiled by John Sutcliffe based on information provided by Silex. 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