Ferberite

specimen number:
2262094

location:
Boulder Co., Colorado, USA

description:
A loose crude bladed crystal of ferberite. Minimal damage present.

The Boulder County Tungsten District, situated in the Front Range of Colorado, is the most significant source of ferberite in the United States. Geologically, the deposits consist of narrow hydrothermal veins hosted within Precambrian granite and gneiss, where the mineralization occurred during the Laramide Orogeny as iron-rich tungsten fluids filled shear zones and fractures. The locality is famous for its ferberite, an iron tungsten oxide that forms distinct black, submetallic, blade-like crystals and drusy aggregates, often characterized by their high density and sharp monoclinic forms. Historically, mining and quarrying activities in the district began in earnest around 1900 after the ore was correctly identified, leading to a massive production boom that peaked during World War I when tungsten was critical for hardening steel. While some operations continued through World War II and the 1950s, most commercial production had ceased by the late 20th century, though the area remain a vital site for geological research and mineral specimen collecting through 2026. Today, the district is remembered for its unique mineralogical signature and its pivotal role in the American industrial war effort.

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