mineral

Herkimer Diamond

Quartz (Silicon Dioxide, SiO2)

Hardness: 7 on Mohs scale. Color: Colorless or clear, sometimes with smoky or hydrocarbon inclusions. Luster: Vitreous to adamantine. Crystal structure: Trigonal, specifically double-terminated quartz crystals with 18 crystal faces. Cleavage: None (conchoidal fracture). Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Luster: Vitreous to adamantine

Identified August 2, 2026More mineral →

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Physical properties

Formation & geological history

Formed in exposed dolostone outcrops through the slow precipitation of silica-rich solutions in cavities within the rock during the Cambrian period, approximately 500 million years ago.

Uses & applications

Used primarily in fine jewelry, crystal healing, and as highly sought-after specimens by mineral collectors.

Geological facts

Despite the name, Herkimer Diamonds are not actual diamonds, but rather exceptionally clear and well-formed quartz crystals. They are famous for their natural double termination and high brilliance without requiring cutting or polishing.

Field identification & locations

Found predominantly in Herkimer County, New York, and surrounding areas. Collectors identify them by searching dolostone vugs (cavities) for their characteristic double-terminated hexagonal shape and exceptional clarity.