Epidote, "Uralite" Amphibole, Magnetite

This specimen showcases deep blocky epidote crystals, though some are contacted around the periphery many more have excellent form and lustre. The epidote crystals, exhibiting their classic chisel-shaped appearance, come from the historic Calumet Mine in Colorado, which is renowned for its epidote specimens. On the underside, the deep green epidotes are complemented by "uralite," a pseudomorph of actinolite (an amphibole) after pyroxene minerals such as diopside or augite. The "uralite" displays a grayish-blue-green colouration. Historically, "uralite" was considered a distinct species but is now classified as part of the amphibole group. At the Calumet Mine, "uralite" crystals are often coated with calcite, which collectors typically dissolve with hydrochloric acid to reveal the underlying structure. This small-cabinet sized specimen also includes a patch of sparkly black microcrystals of magnetite. While Colorado is widely recognized for iconic minerals such as rhodochrosite, amazonite, aquamarine, and gold, the epidotes from this locality remain less familiar to many collectors, making this piece a standout example from a classic American locality.