mineral

Herkimer Diamond

Quartz (Silicon Dioxide, SiO2)

Hardness: 7.5 (harder than standard quartz at 7.0), Color: Clear/Colorless, Luster: Vitreous (glassy), Crystal Structure: Hexagonal with double termination, Cleavage: None/Conchoidal fracture, Specific Gravity: 2.65

Hardness: 7

Identified May 13, 2026More mineral →

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Physical properties

Formation & geological history

Formed in ancient vugs (cavities) within the Little Falls Dolostone during the Cambrian period approximately 500 million years ago. These crystals grew very slowly under high pressure and temperature in a liquid silicate solution.

Uses & applications

Highly prized by mineral collectors and used in jewelry as a substitute for diamonds. Also used in spiritual and metaphysical practices as a 'high-vibration' stone.

Geological facts

These are not actually diamonds but are uniquely double-terminated quartz crystals. They were named for Herkimer County, New York, where they were first discovered in large quantities by white settlers. They often contain black carbon inclusions or fluid inclusions (enhydros).

Field identification & locations

Identify in the field by their natural double termination (points at both ends), exceptional clarity, and 18 distinct crystal facets. They are famously found in Herkimer County, New York, often requiring heavy hammering of dolostone rock.