Heulandite with Mordenite

specimen number:
2063185

location:
Rats Nest claim, Custer Co., Idaho, USA

description:
An attractive example for this well-known locality with light salmon colored crystals of heulandite to 1.5 cm in size, these very lustrous, across the top of a white silky crystallized mordenite matrix. In good condition. This was likely collected in the 1990s. The specimen comes with a previous label from the collection of Ray DeMark.

The Rats Nest claim, situated in the Challis-Bay Horse mining district of Custer County, Idaho, is known for producing fine specimen-grade zeolites through small-scale, hobbyist, and professional mineral collecting rather than commercial ore extraction. Geologically, the area features volcanic and hydrothermal environments where mineral-rich solutions filled cavities and fractures in the host rock, precipitating fine crystals of mordenite and tabular, pinkish to white heulandite. Heulandite itself is a hydrated sodium calcium aluminum silicate framework mineral belonging to the zeolite group, prized by collectors for its distinct coffin-shaped or diamond-like crystal habits often found resting on fibrous mordenite matrices.

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