igneous

Snowflake Obsidian

Volcanic glass containing Cristobalite (SiO2)

Hardness: 5-5.5 on Mohs scale; Color: Black with white or gray patches; Luster: Vitreous/Glassy; Structure: Amorphous (non-crystalline) glass with radial mineral inclusions; Cleavage: None (conchoidal fracture).

Hardness: 5-5
Color: Black with white or gray patches
Luster: Vitreous/Glassy

Identified April 9, 2026More igneous →

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Physical properties

Formation & geological history

Formed through the rapid cooling of felsic lava, which prevents large crystal growth. The 'snowflakes' are formed as the glass begins to devitrify into spherulitic inclusions of cristobalite (a polymorph of silica).

Uses & applications

Primarily used for lapidary work including jewelry (pendants, beads), ornamental carvings, and as a popular semi-precious stone for crystal collectors and metaphysical uses.

Geological facts

The white 'snowflakes' are actually spherulites of cristobalite, a type of quartz. Unlike most obsidian which is stable for a short geological time, the devitrification process shown here marks the beginning of the glass turning back into rock.

Field identification & locations

Identify in the field by its distinct glassy black base and radial white spots. It is commonly found in areas of recent volcanic activity such as the Western United States (Utah, Oregon), Mexico, and Iceland.

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Basalt (extrusive igneous rock) or Diabase (intrusive igneous rock - also known as Dolerite), largely composed of plagioclase feldspar, pyroxene (augite), and sometimes olivine and amphibole. Exact mineralogy would require thin section analysis.

Igneous

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Magnetite

Magnetite (Fe3O4)

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