igneous

Snowflake Obsidian

Volcanic glass containing Spherulite inclusions (primarily Cristobalite, SiO2)

Hardness: 5-5.5 on Mohs scale. Color: Black with white-to-gray 'snowflake' patches. Luster: Vitreous/Glassy. Structure: Amorphous (non-crystalline glass). Cleavage: None (conchoidal fracture).

Hardness: 5-5
Color: Black with white-to-gray 'snowflake' patches
Luster: Vitreous/Glassy

Identified March 14, 2026More igneous →

Identify your own rocks.

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

App Store Google Play

Physical properties

Hardness: 5-5.5 on Mohs scale. Color: Black with white-to-gray 'snowflake' patches. Luster: Vitreous/Glassy. Structure: Amorphous (non-crystalline glass). Cleavage: None (conchoidal fracture).

Formation & geological history

Formed through the rapid cooling of felsic (silica-rich) lava. The 'snowflakes' are spherulite inclusions formed when the glass undergoes partial devitrification, allowing the mineral cristobalite to grow in radiating needle-like patterns.

Uses & applications

Commonly used in jewelry (cabochons, beads), decorative carvings, and as a popular specimen for metaphysical crystal collecting. Historically used for making sharp tools and arrowheads.

Geological facts

Despite being an igneous rock, it is biologically described as a 'glass' because it cools so quickly that crystals cannot form in the matrix. The 'snowflakes' are one of the few instances where crystallization occurs within the cooling glass after formation.

Field identification & locations

Identify by its distinct white patches on a deep black, glassy surface. Common locations include volcanic regions in Utah (USA), Mexico, and Iceland. Collectors should look for sharp conchoidal edges on raw pieces and a high-gloss finish on tumbled stones.

Other igneous specimens

See all

Blue Apatite

Fluorapatite (Ca5(PO4)3F)

mineral

Dark Igneous Rock (Likely Basalt or Diabase)

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

Magnetite

Iron(II,III) oxide (Fe3O4)

mineral

Blue Apatite

Apatite (Group), Ca5(PO4)3(F,Cl,OH)

mineral

Sodalite

Sodalite - Na8(Al6Si6O24)Cl2

mineral

Magnetite

Magnetite (Fe3O4)

mineral