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Hycroft Mine
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Hycroft Gold Mine

The Hycroft gold mine is located in the Sulfur Mining district, 54 miles west of Winnemucca in Humboldt County, Nevada. The mine encompasses approximately 25,320 acres, including both patented and unpatented claims. While in production (1987-1998), Hycroft produced over one million ounces of gold using a surface heap leaching process.

The Hycroft mine is expected to reach steady-state production of 8,300 ounces of gold per month by the end of 2009 at cost of sales per gold ounce sold of $390-$410. The mine is currently evaluating various opportunities to increase the mining rate for oxide mineralization and possible processing options for sulphide mineralization. The mine celebrated it's official grand opening on June 17, 2009, with an inaugural gold pour at the newly built refinery. 



Mining
Hycroft operates twenty four hours a day, seven days a week.  Mining of the Brimstone oxide mineralization is by simple open pit drill, blast and haulage of ore to processing.  Gold and silver is produced utilizing a run-of-mine heap leach process and a Merrill Crowe gold recovery plant.  Based upon historic gold recovery of Brimstone ores, gold recovery is estimated to average 56.6%.

Historically, gold mineralization at Brimstone was thought to be limited to the oxide cap of a large sulfide gold and silver system.  Allied Nevada has completed exploration drilling that has shown a portion of the oxide cap has extensive sulfide gold and silver mineralization lying beneath.  The thickness of the sulfide averages approximately 400 feet; the strike length of the gold and silver sulfide mineralization is approximately 6,000 feet.

Geology and Mineralization
The Hycroft deposit is located in the Nevada Basin and Range geologic province on the western flank of the Kamma Mountains, along the county line between Humboldt and Pershing Counties, Nevada. Tertiary to recent, fault‐controlled, low‐sulfidation gold deposits occur over an area measuring 3 miles in a north‐south direction by 1.5 miles in an east‐west direction.
Based on drilling results, mineralization extends to depths of at least than 330 ft in the outcropping to near‐outcropping portion of the Bay deposit on the northwest side and to over 1000 ft in the Brimstone deposit in the eastern portion of the Hycroft property.
 
Five major north‐northeast trending, west‐dipping, normal fault zones broadly bound gold mineralization. The fault zones are referred to as the Central, Boneyard, Albert, Fire and East Faults. The Lewis, Bay, Central and South Central, Cut 3, and Cut 4 deposits are hosted by the Sulfur Group in the hanging wall of the Central Fault.

The Brimstone Deposit is hosted within the hanging wall of the East Fault. This portion of the deposit has been highly structurally prepared by at least four phases of alteration. Gold mineralization is thought to have occurred during periods of fracture controlled, chalcedony/pyrite/marcasite mineralization. Oxidation appears to be related to a deep acid leaching event.