Calcite with Marcasite

specimen number:
2292268

location:
Ives Quarry, Racine Co., Wisconsin, USA

description:

Colorless scalenohedral crystals of calcite measuring to 2.5 cm in height coming off matrix. These show dark phantom crystals lined with marcasite. In good condition. This is classic material for this Wisconsin locality.

The Ives Quarry, located on the northern periphery of Racine in Racine County, Wisconsin, is a prominent aggregate operation widely recognized for its geological exposures and mineral specimens. Geologically, the quarry cuts through a sequence of four distinct Silurian-age carbonate formations composed predominantly of dolostone, which originally deposited in a marine reef and continental shelf environment roughly 420 million years ago. These strata feature prominent vuggy zones and paleokarst dissolution cavities that host sharp, lustrous calcite crystals, which frequently display dark marcasite phantom inclusions, alongside an abundance of marine fossils such as corals, brachiopods, and crinoids. Industrial quarrying at the site commenced in the 1920s to produce crushed stone and construction aggregate. The historical Ives operations were later integrated into the larger Vulcan Materials Company quarry complex, which has utilized extensive open pits and a subterranean transport tunnel to remain continuously active well into the 2020s.

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