The Copperstone Mine is a high-grade, fully-permitted gold deposit located in mining-friendly Western Arizona, along the Walker Lane Belt. Having historically produced ~500,000 ounces of gold, Copperstone contains existing infrastructure which reduces investment requirements and speeds up the timeline to production.
Arizona is a mining-friendly jurisdiction with a long, rich history of resource extraction, accounting for 65% of copper production in the United States. With ready access to skilled labour and a clear permitting and approval process, it is an optimal location for this project. The Copperstone Mine is located in LaPaz County, in Western Arizona, within the Walker Lane mineral belt where it intersects gold provinces in Southern California and Western Arizona. These provinces host a total known gold endowment of over 40 million ounces of gold. Copperstone is part of a lesser-known, globally significant, high-grade gold province. The property is accessible from Phoenix on Interstate 10 to Quartzsite and from Quartzsite on Route 95.
Geology and Mineralization
Copperstone occurs within the “Basin and Range” province of the South-Western United States. The regional geology is strongly influenced by Tertiary age detachment faults and younger high angle normal faults. The Copperstone gold deposit is related to the Moon Mountain or Copper Peak detachment fault. Gold mineralization at Copperstone occurs principally within the moderate to low-angle Copperstone Fault which has been interpreted to be a listric fault associated with the underlying Moon Mountain detachment fault. Gold occurs as native flakes within fault breccia, gouge and shear zones related to the faulting. The wall and host rocks are typically Triassic sediments and Jurassic quartz latite volcanics. Gold is commonly associated with hematite, chlorite, quartz, manganese oxide and copper oxide mineralization. In the case of the Copperstone Mine, the gold is not encapsulated in sulphides or silica, and the ores do not contain active carbon. This means that the ores at Copperstone are not refractory. This is a consequence of the fact that these ores appear to be comprised of “original”, or “primary”, or “hypogene” oxides minerals. Copperstone ores are not a weathered or oxidized material that started off as a sulphide (which is the common case). The oxides, when ground in the mill, free the gold up to be recovered in the gravity or flotation circuits. These ores also respond very well to cyanide processes. The Copperstone Mine produced nearly one-half million ounces of gold between 1987 and 1993 through open pit mining. Existing infrastructure which remains from this time, or which has been subsequently installed by Bonanza, is considerable and serves to reduce the current capital requirements for the mine. Existing infrastructure includes a 69 KV power line and substation, and three water wells, all sufficient for the new mine at Copperstone. Additional infrastructure on site includes offices, maintenance shops and a laboratory building.
Infrastructure and Development
The Copperstone Mine produced nearly one-half million ounces of gold between 1987 and 1993 through open pit mining. Existing infrastructure which remains from this time, or which has been subsequently installed by the Company’s predecessor and wholly owned subsidiary, American Bonanza Gold Corp., is considerable and serves to reduce the current capital requirements for the mine. Existing infrastructure includes a 69 KV power line and substation, and three water wells, all sufficient for the proposed operations at Copperstone. Additional infrastructure on site includes offices, maintenance shops and a laboratory building (permitted tailings facility, processing facility and mill).