Barite with Calcite

specimen number:
2262233

location:
Stoneham, Weld Co., Colorado, USA

description:
Gemmy blue terminated crystal of barite 1.8 cm in length set nicely up on a crystalline calcite matrix. This is in good condition. Nice matrix example for this Colorado classic.

The Stoneham barite locality, situated in Weld County, Colorado, is a highly celebrated Western site renowned for producing elegant, gem-quality crystals of sky-blue barite. Geologically, these unique specimens occur within the late Eocene-age Chadron Formation of the White River Group, which consists primarily of fine-grained volcanic ash layers and tuffaceous siltstones. Over millions of years, the slow downward percolation of alkaline groundwater dissolved barium and sulfate ions from the surrounding volcanic sediments, allowing the minerals to precipitate into open clay pockets, shrinkage cracks, and chalcedony-lined nodules as beautiful, elongated tabular prisms up to several inches long. Historically, the discovery of these delicate blue crystals dates back to the late 19th century, with formal mineralogical documentation occurring as early as the 1880s. Unlike large-scale industrial operations, the site has never been subjected to heavy corporate mining or underground quarrying, remaining instead a seasonal surface-digging locality worked by independent specimen miners, commercial dealers, and museum curators under specific mineral leases from the early 1900s through the late 20th century.

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