Barahonaite-Al with Opal

specimen number:
2354066

location:
80 level adit, Gold Hill Mine, Tooele Co., Utah, USA

description:
Two areas across the top of this matrix are covered with light blue botryoidal micro crystalline barahonaite-al. Each area measures approximately 2.0 x 1.0 cm in size. Minor colorless opal is present. In great condition, and a very choice example for this rare mineral. The specimen comes with a previous label from the collection of Eric Laskowski.

The Gold Hill Mine, located in the Deep Creek Mountains of Tooele County, Utah, is set within Paleozoic limestone host rocks intruded by Late Jurassic granodiorite and Tertiary quartz monzonite stocks. Originally worked starting in the late 19th century primarily for gold, copper, lead, and silver, the locality later became a major source of arsenic and tungsten during World War I and World War II. Hydrothermal activity and subsequent extensive oxidation created a world-renowned suite of secondary supergene arsenate minerals, making the site famous among micro-mineral collectors. Among these rare secondary phase minerals is barahonaite-Al, an extremely scarce hydrous calcium copper aluminum arsenate that occurs as light blue microcrystalline crusts and spherical aggregates within oxidized cavities, notably recovered from the 80-foot adit level of the mine.

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