Orpiment

specimen number:
9273037

location:
Twin Creeks Mine, Humboldt Co., Nevada, USA

description:

Gorgeous example for the species with slightly translucent lustrous brilliant orange crystals of orpiment across the front of matrix. Collected in the late 1990s. This is in super condition.

The Twin Creeks mine, situated along the eastern flank of the Osgood Mountains within Humboldt County, Nevada, is a massive open-pit gold mining complex celebrated for producing immense bullion wealth and spectacular collector specimens of bright yellow orpiment. Geologically, this major deposit is a premier example of a Carlin-type sediment-hosted disseminated gold system, localized within heavily folded and faulted Paleozoic sedimentary sequences including the Ordovician Comus Formation and the Mississippian-Pennsylvanian Valmy Formation. Mineralization occurred during the Eocene epoch when deep-seated, gold-bearing hydrothermal fluids ascended through regional fault systems, reacting with the decarbonated silty limestones to deposit sub-microscopic gold within arsenian pyrite, accompanied by late-stage, low-temperature fluids that formed large pockets of coarse, crystallized arsenic sulfides. Historically, the operation was formed in 1993 through the consolidation of two adjacent properties: the Chimney Creek mine, discovered by Gold Fields Mining Company in 1985, and the Rabbit Creek mine, discovered by Santa Fe Pacific Gold Corporation in 1987. The consolidated asset transitioned through Newmont Mining Corporation ownership and became a core operating unit of the Nevada Gold Mines joint venture, a partnership between Barrick Gold and Newmont launched in 2019. Through 2026, the Twin Creeks mine continues active large-scale open-pit and underground operations, utilizing advanced autoclave and roasting facilities to process refractory ores while serving as a foundational global geological benchmark for studying structural controls and arsenic-rich mineral zoning in sediment-hosted gold systems.

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