mineral

Herkimer Diamond

Quartz (Silica - SiO2)

Hardness: 7.5 on Mohs scale (harder than standard quartz at 7.0); Color: Colorless/transparent to smoky; Luster: Vitreous (glassy); Crystal structure: Hexagonal with double termination; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7
Color: Colorless/transparent to smoky
Luster: Vitreous (glassy)

Identified March 25, 2026More mineral →

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Physical properties

Formation & geological history

Formed roughly 500 million years ago in the Cambrian Little Falls Dolostone. These crystals grew very slowly within vugs (pockets) filled with water and organic acids, often containing anthraxolite inclusions.

Uses & applications

Primarily used in jewelry, as gemstone specimens for collectors, and in metaphysical practices. Unlike most quartz, they are naturally faceted, making them popular for 'raw' jewelry settings.

Geological facts

They are not actually diamonds, which are carbon; they are quartz. The name comes from Herkimer County, New York, where they were first discovered. They are unique because they are naturally double-terminated (pointed at both ends).

Field identification & locations

Identify in the field by looking for the 18-facet double-terminated shape in sedimentary rock (Dolostone). They are primarily found in Herkimer County, NY, and surrounding areas. Collectors should look for 'vugs' or pockets within the rock.