Calcite

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Lustrous gemmy yellow scalenohedral crystals of calcite measuring to 4.0 cm in size across the top of matrix. This is in good condition.The Red Cliff Cave locality, situated above the Red Cliff Campground in the Gallatin Canyon of Gallatin County, Montana, is a specialized mineral site known for its production of calcite specimens. Geologically, the cave developed within the Mississippian-aged Mission Canyon Limestone, which underwent dissolution from fresh water and carbonic acid during periods of subaerial exposure prior to being buried by the iron-oxide-rich muds of the overlying Amsden Formation. This dissolution created karstic openings, caverns, and vugs where calcium-carbonate-bearing groundwaters later precipitated coarse, rhombohedral and dogtooth calcite crystals along the cave walls and surrounding hillside. The site never operated as a commercial, industrial-scale metal mine or quarry, serving instead as a localized source for field collectors and rockhounds starting in the mid-twentieth century. Hand extraction of loose calcite chunks from the steep slopes and within the cave occurred regularly until the early 1970s, when unauthorized blasting heavily damaged the primary cave interior, though seasonal surface collecting for loose calcite continues on the surrounding public lands.