Gypsum

specimen number:
2062965

location:
Wilson Lake spillway area, Russell Co., Kansas, USA

description:
Neat locality example for the species, a loose glassy gem double terminated crystal of gypsum. Perfect all around. The specimen comes with a previous label from the collection of Ray DeMark.

The Wilson Lake spillway area in Russell County, Kansas, exposes Cretaceous sedimentary strata, primarily featuring the Dakota Formation, Graneros Shale, and Greenhorn Limestone. These geologic layers formed in shallow marine and coastal environments millions of years ago, leaving behind rich fossil materials and extensive shale beds. Rather than being a commercial mining district, the site gained recognition through earth excavation for the dam and spillway, which exposed weathered zones where collector interest centers on crystal formations. Transparent to translucent gypsum crystals, particularly clear selenite varieties and related mineral growths, naturally form and weather out of the dark marine shales like the Graneros member. While amateur rockhounds occasionally scout the exposed slopes and spillway cuts for these specimens, the land is strictly managed by the U.S. Army Corps of Engineers, which generally prohibits the removal or collection of rocks, minerals, and fossils from the immediate dam and spillway zones.

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