mineral

Herkimer Diamond

Quartz (Silicon Dioxide, SiO2)

Hardness: 7.5 on Mohs scale (harder than most quartz); Color: Clear to grayish with black inclusions; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (doubly terminated); Cleavage: None.

Hardness: 7
Color: Clear to grayish with black inclusions
Luster: Vitreous (glassy)

Identified June 7, 2026More mineral →

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Physical properties

Hardness: 7.5 on Mohs scale (harder than most quartz); Color: Clear to grayish with black inclusions; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (doubly terminated); Cleavage: None.

Formation & geological history

Formed in the Little Falls Dolomite from the Cambrian period (~500 million years ago). They grew very slowly in sediment cavities (vugs) lined with drusy quartz.

Uses & applications

Primarily used for high-end jewelry, metaphysical collections, and lapidary art. They are highly sought after by mineral collectors for their natural brilliance.

Geological facts

Unlike standard quartz which grows from a host rock and has only one point, Herkimer Diamonds are doubly terminated, meaning they have points on both ends. This occurs because they grew with little to no contact with their host rock.

Field identification & locations

Identified by their exceptional clarity and 18-faceted double-terminated shape. They are found almost exclusively in and around Herkimer County, New York, USA.