Variscite

specimen number:
2292180

location:
Lucin, Box Elder Co., Utah, USA

description:
A massive piece of attractive green variscite, this polished in certain areas to show the interior color. Classic material for this locality.

The Lucin mining district, situated in the Pilot Range of western Box Elder County, Utah, is a historical mining locality widely recognized for its notable copper and phosphate deposits. Geologically, the district features Paleozoic limestone, dolomite, and quartzite formations that were intruded by igneous rocks, leading to complex faulting, hydrothermal alteration, and the formation of secondary mineral zones within fractures and solution cavities. Small-scale mining began in the area around 1872, initially targeting copper and silver-lead ores, which led to the establishment of the nearby boomtown of Lucin. While copper production largely waned by the early twentieth century, specialized open-pit quarrying and trenching emerged to extract highly prized secondary phosphate minerals, with sporadic commercial and artisanal operations continuing from the 1900s through the mid-twentieth century.

Variscite is a hydrated aluminum phosphate mineral that typically forms as a secondary mineral near the surface through the alteration of phosphate-bearing rocks by meteoric water. Geologically, it occurs as nodular masses, microcrystalline crusts, or vein fillings within fractured, aluminum-rich sedimentary rocks like shales and cherts, where circulating fluids supply the necessary phosphorus and aluminum. The mineral is highly valued for its striking apple-green to blue-green color, which is primarily caused by trace amounts of chromium and iron replacing aluminum in the crystal structure. Variscite is frequently associated with other secondary phosphate minerals like wardite and crandallite, and it is primarily collected and quarried for use as a semi-precious gemstone and ornamental carving material.

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