mineral

Herkimer Diamond

Quartz (Silicon Dioxide, SiO2)

AI-generated identification · may be incorrect

Hardness: 7.5 (slightly harder than common quartz); Color: Transparent to colorless; Luster: Vitreous; Crystal Structure: Hexagonal (doubly terminated); Cleavage: None; Specific Gravity: 2.65

Hardness: 7
Color: Transparent to colorless
Luster: Vitreous

Identified February 14, 2026More mineral →

Explore Herkimer Diamond in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 7.5 (slightly harder than common quartz); Color: Transparent to colorless; Luster: Vitreous; Crystal Structure: Hexagonal (doubly terminated); Cleavage: None; Specific Gravity: 2.65

Formation & geological history

Formed in cavities (vugs) within Little Falls Dolostone during the Cambrian period, approximately 500 million years ago. They crystallize from silica-rich hydrothermal solutions as the surrounding rock cools and fractures.

Uses & applications

Used primarily for jewelry (as natural faceted stones), metaphysical/healing collecting, and as a popular specimen for mineral enthusiasts.

Geological facts

Despite the name, they are not diamonds but quartz. They are called 'diamonds' due to their natural clarity and faceted shape. Some specimens contain 'enhydro' inclusions, which are ancient water bubbles trapped inside the crystal.

Field identification & locations

Identify in the field by looking for double-terminated (pointed at both ends) crystals in dolostone matrix. Most famously found in Herkimer County, New York, but similar quartz crystals are found in Arizona and Pakistan.