Pararealgar replacing Realgar
specimen number:
2102268
location:
Getchell Mine, Humboldt Co., Nevada, USA
description: The Getchell Mine, located in the Potosi District of Humboldt County, Nevada, is a premier example of a Carlin-type sediment-hosted gold deposit. Geologically, the mine is situated along the Getchell Fault at the eastern edge of the Osgood Mountains, where hydrothermal fluids deposited microscopic gold along with arsenic, antimony, and mercury minerals within Paleozoic limestone and shale. The site is mineralogically famous for its spectacular specimens of realgar and orpiment, and it is a notable locality for pararealgar, a bright orange-yellow mineral that forms as a light-induced alteration product of realgar. Historically, the mine was discovered in 1934 and began significant production in 1938, serving as a vital source of gold and strategic tungsten during World War II. Operations fluctuated throughout the mid-20th century due to the refractory nature of the ore, but a major revival occurred in the 1980s with the development of modern open-pit and underground mining techniques. Today, the Getchell Mine remains part of a massive industrial complex under the Nevada Gold Mines joint venture, continuing its legacy as one of the most productive gold and arsenic-rich mineral systems in North America.
Prismatic crystals of what were once realgar measuring to almost 3.0 cm in size in the process of being replaced by yellowish pararealgar. Nice for this classic Nevada locality.
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