Metaautunite

specimen number:
2262089

location:
Daybreak Mine, Spokane County, Washington, USA

description:
Yellow green platy crystals of metaautunite in a cluster without matrix. In good condition.

The Daybreak Mine, located on the western flank of Mount Spokane in Spokane County, Washington, is a renowned pegmatite deposit characterized by its unique secondary uranium mineralization. Geologically, the mine is situated within a weathered granitic pegmatite where primary uranium minerals underwent oxidation and hydration to form spectacular concentrations of secondary phosphates. The locality is world-famous for its meta-autunite, a hydrated calcium uranium phosphate that occurs as large, vibrant neon-green to yellow micaceous plates and coarse, fan-like aggregates that exhibit intense yellowish-green fluorescence under ultraviolet light. Historically, mining and quarrying at the site began in 1955 after the initial discovery of radioactive ore by the Dawn Mining Company, sparking a localized uranium rush in the Pacific Northwest. The mine operated most actively during the mid-to-late 1950s, producing significant quantities of ore for the Atomic Energy Commission and providing some of the finest museum-quality autunite specimens ever recovered. While commercial extraction for industrial uranium concluded decades ago, the Daybreak Mine remains a premier destination for mineralogists and collectors through 2026, serving as a classic reference site for the study of secondary uranium crystal habits in pegmatitic environments.

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