Gold Mining in western Arizona staged for a productive New Year
The spot price for an ounce of gold in Dec. 2017 is ~ $1,247; not as inviting as the high-water mark of $1,837 of Sept. 2011. Nonetheless, the current mining economy is driving gold exploration and production in western Arizona. Going forward in 2018, the Kerr Mine Inc.’s Copperstone Mine and Northern Vertex’s Moss Gold-Silver project promise a strong showing as major gold producers.
Copperstone was first discovered in the mid- to late-1980s, long after most of Arizona’s gold-mining districts had played out. In contrast, gold production on the Moss vein dates to 1863-1864. Northern Vertex’s program is just the latest in a series of mines at the Moss.
Nevada’s standing as the number one gold producer in the U.S. remains secure, but the Moss and Copperstone Mines represent a big step forward for gold production in Arizona.
Copperstone Mine | La Paz County, Arizona
Kerr Mine Inc. is at work re-opening the Copperstone Mine in La Paz County, Arizona. The mine is fully permitted, and essential infrastructure and water resources are available on site. Kerr Mines Inc. Phase 1 drilling program confirms significant gold mineralization at Copperstone (Toronto, 5 Dec. 2017)
Copperstone started as an underground mine in 1988, before transitioning into an open pit mine – where it produced nearly ‘one-half million ounces of gold’. Kerr Mine Inc. is returning the Copperstone to its underground roots. In 1988, it was estimated that the mine would yield 510,000 troy ounces of gold worth $230 million in 1988 dollars. (Actual yield from the open pit mine was over 500,000 ounces of gold.)
According to Spencer and others (1988), ‘Copperstone gold deposit lies within the hanging wall of the Moon Mountains detachment fault … ‘. The gold deposit originated from processes common to detachment faults as described in Spencer and others (1988) p. 2. A report by Nyal Niemuth notes that ‘Mineralization is a tabular deposit striking N30W and dipping 32NE with ore control by faults and brecciation and detachment faulting.’
Northern Vertex Moss Mine Gold-Silver Project
Joe Bardswich, project manager for the Moss Mine project, has more than 30-years of mining experience, including mine construction, engineering and operations. (Joe joined Lee Allison on the Arizona Mining Review on 26 Nov. 2014, to chat about the Moss Mine.)
The Moss is a gold-silver epithermal vein system, comprising a stockwork of brecciated, low sulfide ore. The mine is situated in the San Francisco Mining District of Mohave County, a half-hour drive from Bullhead City. Gold mineralization is largely hosted in the 18.5 million-year-old Moss Quartz Monzonite porphyry.
A pilot test in early 2014 involved cyanide leaching of 125,000 tons of crushed ore. The ore yielded 1.6 grams of gold/ton and 16 grams of silver/ton. Gold recovery approached 82%, while silver lagged at ~ 38%.
US Geological Survey Bulletin 1857- I includes a 27-page report by Ed Dewitt, Jon Thorson and Robert Smith on the ‘Geology and Gold Deposits of the Oatman District, Northwestern, Arizona.
Spencer and others, 1988, The Copperstone Mine: Arizona’s New Gold Producer. Arizona Bureau of Geology and Mineral Technology Fieldnotes, Summer 1988.
Mindat.org, Copperstone Mine, La Paz District, Dome Rock Mts, La Paz County, Arizona, USA.
DeWitt and other, 1991, Geology and gold deposits of the Oatman District, NW Arizona. US Geological Survey Bulletin 1857-I, p. I1-I27.
Posted 11 Dec 2017 (MC)