Pyrite with Calcite

specimen number:
9892163

location:
Sweetwater Mine, Viburnum Trend, Reynolds Co., Missouri, USA

description:
A grouping of lustrous golden cubic crystals of pyrite measuring to 1.3 cm on edge, these on a small amount of matrix and hosting minor crystallized calcite. In good condition, some of the calcite crystals on the lower backside of the piece are cleaved.

The Sweetwater Mine, situated in the southern portion of the Viburnum Trend in Reynolds County, Missouri, is a world-class Mississippi Valley-type deposit hosted within the porous platform carbonates of the Upper Cambrian Bonneterre Dolomite. Mineralization formed through ancient hydrothermal fluid migration, concentrating metal sulfides within ancient reef and algal mound structures. Modern exploration of the district began in the mid-1950s, leading to major underground operations such as Sweetwater (originally developed as the Ozark Lead Company mine) starting production in the late 1960s to extract valuable ore minerals. Beyond its significant industrial output of lead, copper, and zinc, the mine became globally renowned among mineral collectors for yielding pristine, highly sculptural crystals, particularly large scalenohedral calcite prisms, lustrous galena, and associated accessory minerals.

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