Calcite

specimen number:
2292279

location:
Alzada, Carter Co., Montana, USA

description:
Attractive slightly translucent grouping of stalactitic calcite. This is in very good condition. Classic material for this locality, likely collected in the 1970s.

The Alzada area, situated in the far southeastern corner of Carter County, Montana, is celebrated among mineral collectors for producing unique specimens of vibrant orange stalactitic calcite. Geologically, these highly lustrous, microcrystalline formations developed within localized underground dissolution cavities and fracture systems hosted inside Upper Cretaceous sedimentary shale and limestone units. Over thousands of years, meteoric waters dissolved calcium carbonate from the upper strata and dripped into open subterranean voids, slowly depositing concentric layers of calcite to form distinct stalactitic columns, with trace elements or micro-inclusions of iron oxides providing the characteristic bright orange coloration. Small-scale, localized specimen mining and surface quarrying of these cave-like pockets gained popularity primarily during the late twentieth century, particularly during the 1970s and 1980s, when local landowners and field collectors systematically excavated the pockets to supply the collector market. These specialized surface operations were relatively short-lived and reached their peak decades ago, leaving the locality inactive today with old collected material supplying the secondary market.

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