mineral

Herkimer Diamond

Quartz (Silicon Dioxide, SiO2)

Hardness: 7.5 Mohs (harder than most quartz); Color: Clear to smoky; Luster: Vitreous; Crystal Structure: Hexagonal (doubly terminated); Cleavage: None; Specific Gravity: 2.65.

Hardness: 7
Color: Clear to smoky
Luster: Vitreous

Identified July 9, 2026More mineral →

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Physical properties

Hardness: 7.5 Mohs (harder than most quartz); Color: Clear to smoky; Luster: Vitreous; Crystal Structure: Hexagonal (doubly terminated); Cleavage: None; Specific Gravity: 2.65.

Formation & geological history

Formed approximately 500 million years ago in the Cambrian Little Falls Dolostone. These crystals grow slowly in vugs (cavities) within the host rock, allowing for their unique double-terminated shape.

Uses & applications

Highly prized by mineral collectors, used in jewelry as an alternative to diamonds, and popular in metaphysical and crystal healing communities.

Geological facts

Despite the name, they are not diamonds but exceptionally clear quartz crystals. They are called 'doubly terminated' because they have natural points at both ends, which is rare for quartz.

Field identification & locations

Identify by their natural 18-faceted double-terminated shape and exceptional clarity. They are primarily found in Herkimer County, New York, though similar crystals exist elsewhere.