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Obsidian (Snowflake) identification and geology

Black obsidian containing white spherulitic inclusions of cristobalite that create a snowflake pattern. Texture: Glassy with spherulites. Rock type: Igneous Extrusive. Grain size: Glassy. Minerals present: Volcanic glass, Cristobalite. Formation: Forms when obsidian undergoes partial devitrification, with cristobalite crystallizing as radial clusters. Common geological settings: Utah, Oregon USA , Mexico, Iceland; found in rhyolitic lava flows. Common look-alikes and related entries: Obsidian, Rhyolite, Perlite.

Sources, scope & corrections

These authoritative resources support category-level nomenclature, terminology, identification methods, and safety. When a specimen-specific safety warning appears, the public-health source listed here directly supports that precaution. They are not line-by-line citations for every other property on this entry, and natural specimens vary.

Editorial owner
GeoMiner
Last updated
2026-02-10T20:31:42.828172+00:00
Review status
Published; not independently peer-reviewed
  • Rocks — U.S. National Park Service. Authoritative overview of rock groups, the rock cycle, and geologic processes.
  • Can you identify my rock or mineral? — U.S. Geological Survey. Identification limitations and routes to in-person professional verification.

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Common questions

What is Obsidian Snowflake?
Black obsidian containing white spherulitic inclusions of cristobalite that create a snowflake pattern.
How can you identify Obsidian Snowflake?
Compare several properties rather than relying on colour alone. This entry records rock type: Igneous Extrusive; texture: Glassy with spherulites; grain size: Glassy; common minerals: Volcanic glass, Cristobalite. Confirm an important identification with additional field tests or qualified laboratory work.
How does Obsidian Snowflake form?
Forms when obsidian undergoes partial devitrification, with cristobalite crystallizing as radial clusters.
Where is Obsidian Snowflake commonly found?
Utah, Oregon USA , Mexico, Iceland; found in rhyolitic lava flows.
What is Obsidian Snowflake commonly confused with?
Obsidian Snowflake may be confused with Obsidian, Rhyolite, Perlite. Compare multiple diagnostic properties because colour and surface appearance can overlap.

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