mineral

Herkimer Diamond (Quartz Crystal)

Silicon Dioxide (SiO2)

Hardness: 7.0 on Mohs scale; Color: Colorless/Transparent; Luster: Vitreous; Crystal structure: Double-terminated hexagonal prisms; Cleavage: None; Specific gravity: 2.65.

Hardness: 7
Color: Colorless/Transparent
Luster: Vitreous

Identified May 10, 2026More mineral →

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Physical properties

Hardness: 7.0 on Mohs scale; Color: Colorless/Transparent; Luster: Vitreous; Crystal structure: Double-terminated hexagonal prisms; Cleavage: None; Specific gravity: 2.65.

Formation & geological history

Formed in vugs or cavities within the Little Falls Dolostone (sedimentary rock) during the Cambrian period. They crystallized from hydrothermal solutions roughly 500 million years ago.

Uses & applications

Mostly used in jewelry (as raw or set stones), metaphysical collecting, and as a popular specimen for mineral enthusiasts.

Geological facts

They are not actually diamonds but are called so due to their natural clarity and diamond-like faceted shape. Unlike most quartz, they grow with two natural points (double-terminated).

Field identification & locations

Identify by their double-terminated points and exceptional clarity. They are famously found in and named after Herkimer County, New York.

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