mineral

Herkimer Diamond (Quartz)

Silicon Dioxide (SiO2)

Hardness: 7.0 on Mohs scale. Color: Colorless to smoky. Luster: Vitreous/Glassy. Crystal Structure: Hexagonal (double-terminated). Cleavage: None (conchoidal fracture). Specific Gravity: 2.65.

Hardness: 7
Color: Colorless to smoky
Luster: Vitreous/Glassy

Identified April 6, 2026More mineral →

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Physical properties

Hardness: 7.0 on Mohs scale. Color: Colorless to smoky. Luster: Vitreous/Glassy. Crystal Structure: Hexagonal (double-terminated). Cleavage: None (conchoidal fracture). Specific Gravity: 2.65.

Formation & geological history

Found in the Little Falls Dolostone (sedimentary rock) of the Mohawk River Valley in New York. They formed approximately 500 million years ago in cavities (vugs) lined with drusy quartz.

Uses & applications

Primarily used as jewelry in its natural state, mineral collecting, and in spiritual/metaphysical practices.

Geological facts

They are not actually diamonds, but are called so because of their natural clarity and diamond-like shape. They were first discovered in large quantities during the early 1800s in Herkimer County, New York.

Field identification & locations

Identify by their double-terminated (pointed at both ends) hexagonal shape and exceptional clarity. They are most famously found in New York, USA, but similar quartz crystals occur in Pakistan and China.