Calcite

specimen number:
2063577

location:
Irving Materials Quarry, Anderson, Madison Co., Indiana, USA

description:
A superb Midwest classic, a glassy gemmy light amber colored twinned crystal of calcite measuring 2.2 x 2.2 x 2.0 cm in size along one edge of matrix. This is in very good condition. At what at first appears to maybe be damaged near the termination is completely natural crystallization. These are incredibly rare to find still attached on matrix, they were almost only available as loose crystals. This is a rare example that is also attractive. The specimen comes with a previous label from the collection of Ray DeMark.

Located in Madison County, Indiana, the Irving Materials Quarry (also known as the Anderson Quarry) exposes Silurian-age dolostones and limestones belonging to the Salamonie Dolomite and Pipe Creek Falls Formation. Modern quarrying operations at the site extract high-purity crushed aggregate, revealing solution cavities, vugs, and open fractures formed by historic hydrothermal fluid activity. Within these mineralized pockets, collectors have long targeted exceptional calcite crystals, which are famous among Midwest collectors for displaying prominent scalenohedral habits and sharp twinned forms, including classic contact and penetration twins. The quarry remains an active commercial site with restricted public access, but preserved specimens from past working faces are highly prized for their lustrous, amber-to-clear twinned calcite crystals resting on fine-grained dolomite matrix.

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