Dark volcanic glass with a resinous to pitchy luster, containing more water than obsidian but less than perlite. Texture: Glassy with resinous luster. Rock type: Igneous Extrusive. Grain size: Glassy. Minerals present: Hydrated volcanic glass, Feldspar microlites. Formation: Forms from rapid cooling of silicic lava with moderate water content. Common geological settings: Scotland Arran , Iceland, New Zealand; found in rhyolitic to trachytic volcanic areas. Common look-alikes and related entries: Obsidian, Perlite, Basalt glass.
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Glassy rocks — Place this specimen in a broader field-identification workflow.
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
2026-03-30T14:38:16.306085+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.
Dark volcanic glass with a resinous to pitchy luster, containing more water than obsidian but less than perlite.
How can you identify Pitchstone?
Compare several properties rather than relying on colour alone. This entry records rock type: Igneous Extrusive; texture: Glassy with resinous luster; grain size: Glassy; common minerals: Hydrated volcanic glass, Feldspar microlites. Confirm an important identification with additional field tests or qualified laboratory work.
How does Pitchstone form?
Forms from rapid cooling of silicic lava with moderate water content.
Where is Pitchstone commonly found?
Scotland Arran , Iceland, New Zealand; found in rhyolitic to trachytic volcanic areas.
What is Pitchstone commonly confused with?
Pitchstone may be confused with Obsidian, Perlite, Basalt glass. Compare multiple diagnostic properties because colour and surface appearance can overlap.
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