Rhyolite
Rhyolite (High-silica volcanic rock)
igneous
Category
Igneous Rock (Volcanic Glass)
Browse igneous rock (volcanic glass) specimens identified by the Rock Identifier community.
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Common Opal in Host Rock
Hydrated Silica (SiO2·nH2O)
mineraloid
Rhyolite
Rhyolite (High-silica volcanic rock)
igneous
Likely obsidian (rough fragment)
Volcanic glass, predominantly silica-rich rhyolitic composition (SiO₂-rich, noncrystalline)
igneous
Quartz Vein in Rhyolite
Silicon Dioxide (SiO2) in extrusive igneous rock
igneous
Pumice
Pumice (Vesicular Rhyolite/Andesite)
igneous
Quartz vein in weathered host rock
Quartz (SiO₂), likely in a weathered metamorphic or igneous matrix
mineral
Pumice
Pumice (Amorphous volcanic glass)
igneous
Pumice
Pumice (extrusive volcanic rock)
igneous
Pumice
Pumice (SiO2)
igneous
Granite pebble
Granite; chiefly quartz, feldspar, and mica
igneous
Pumice
Pumice (Vesicular Felsic to Intermediate Volcanic Rock)
igneous
Pumice
Vesicular Rhyolite / Glassy Igneous Rock
igneous
Black Obsidian
Volcanic Glass (SiO2 + impurities)
igneous
Pumice
Pumice (Vesicular Felsic Igneous Rock)
igneous
Snowflake Obsidian
Volcanic glass with Phenocrysts (SiO2 with Cristobalite inclusions)
igneous
Pumice
Pumicite
igneous
Basalt Pebble
Extrusive Igneous Rock (Mafic)
igneous
Snowflake Obsidian
Volcanic Glass with Cristobalite inclusions
igneous
Obsidian
Volcanic Glass (felsic composition)
igneous
Vesicular volcanic rock (likely pumice or scoria)
Vesicular volcanic rock; composition cannot be determined from the image, but likely pumice or scoria
igneous
Pumice
Pumice, a highly vesicular volcanic glass, commonly rhyolitic to dacitic in composition
igneous
Pumice
Pumice (Amorphous volcanic glass)
igneous
Obsidian-like volcanic rock (likely basaltic volcanic glass)
Basaltic obsidian or tachylite; composition chiefly volcanic glass with plagioclase and pyroxene
igneous
Polished black stone, likely basalt or basaltic glass
Fine-grained basalt (possibly devitrified volcanic glass); mainly plagioclase and pyroxene, with iron-titanium oxides
igneous
Pumice
Pumice (a vesicular volcanic glass)
igneous
Obsidian
Obsidian (Amorphous volcanic glass)
igneous
Pumice
Pumice (Volcanic Rock / Glass Froth)
igneous
Pumice
Pumice (Volcanic Rock / Glass Froth)
igneous
Snowflake Obsidian
Spherulitic Volcanic Glass (SiO2 + impurities)
igneous
Red jasper or glassy volcanic rock (uncertain)
Likely hematite-rich jasper/chert; possibly obsidian with iron-oxide staining
igneous
Obsidian with Cristobalite
Volcanic Glass (Amorphous Silicon Dioxide) with Cristobalite inclusions
igneous
Pumice
Pumice (Vesicular Felsic Igneous Rock)
igneous
Quartz Druzy
Crystalline Silicon Dioxide (SiO2)
mineral
Pumice
Pumice (Vesicular volcanic glass)
igneous
Granite or granitic gneiss
Quartz–feldspar–mica granitoid; possibly foliated gneiss
igneous
Pumice
Pumice (Amorphous volcanic glass)
igneous
Pumice
Pumice (Vesicular volcanic glass)
igneous
Pumice
Pumice (volcanic glass froth)
igneous
Pumice
Pumice (SiO2 + Al2O3 + Fe2O3)
igneous
Basalt
Basalt
igneous
Pumice
Pumicite (Volcanic glass with vesicular texture)
igneous