Durangite

specimen number:
9302321

location:
Thomas Range, Juab Co., Utah, USA

description:

Very good example for the species, orange crystals of durangite on matrix. In good condition. Hematite is present as well.

The Thomas Range, located in Juab County, Utah, is a prominent volcanic mountain range renowned for its diverse assemblage of rare volcanic minerals, particularly top-quality topaz, bixbyite, pseudobrookite, and red beryl. Geologically, the range is composed of thick sequences of Cenozoic rhyolitic lava flows, tuffs, and breccias, with mineral growth occurring within gas cavities, or vugs, during the cooling and crystallization of fluorine-rich topaz rhyolites approximately six to seven million years ago. While indigenous peoples and early explorers collected loose crystals from the surface, formal claims and organized specimen mining at localities like Topaz Mountain began in the late nineteenth century and have continued without interruption into the 2020s through a mix of private mining ventures, commercial specimen extraction, and popular public-access collecting areas.

Durangite is an exceedingly rare sodium aluminum arsenate mineral containing fluorine that typically occurs as small, translucent, reddish-orange to dark red monoclinic crystals. Geologically, it forms as a rare accessory phase in highly fractionated, fluorine-rich granitic pegmatites and associated tin-bearing volcanic rhyolite deposits, where arsenic-bearing fluids react with lithium and fluorine concentrations during late-stage hydrothermal crystallization. The mineral was first discovered in 1869 at the Barranca tin mine in Durango, Mexico, which serves as its type locality, and it remains a highly sought-after species by specialized mineral collectors due to its scarcity and distinctive coloration.

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