Rhyolite
Rhyolite (Extrusive Felsic Igneous Rock)
igneous
Category
Igneous Rock (Volcanic Glass)
Browse igneous rock (volcanic glass) specimens identified by the Rock Identifier community.
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Polished dark stone, likely basalt
Basalt; chiefly plagioclase feldspar, pyroxene, and commonly olivine
igneous
Pumice
Vesicular Rhyolite or Dacite
igneous
Vesicular volcanic rock, likely scoria
Scoria; composition commonly basaltic to andesitic, rich in plagioclase and pyroxene
igneous
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
igneous
Quartz Vein in Host Rock (Breccia/Rhyolite)
Silicon Dioxide (SiO2) with matrix
Mineral in Igneous/Sedimentary host
Obsidian
Volcanic Glass (Amorphous Silicon Dioxide)
igneous
Basalt River Stone
Basaltic Igneous Rock
igneous
Olivine-rich Basalt with Peridotite Xenoliths
Porphyritic Basalt containing Dunite/Peridotite (Mg,Fe)2SiO4
igneous
Basalt with Scoria
Amygdaloidal Basalt / Vesicular Basalt
igneous
Snowflake Obsidian
Volcanic glass with Cristobalite inclusions (70–75% SiO2)
Igneous
Pyrite-bearing Rock
Iron Sulfide (FeS2)
mineral
Snowflake Obsidian
Volcanic Glass with Spherulite inclusions (Amorphous SiO2 + Cristobalite)
igneous
Limonite Stained Basalt
Hydrated Iron Oxide on Mafic Volcanic Rock (FeO(OH)·nH2O)
igneous
Brecciated jasper (likely ocean jasper or rhyolitic jasper)
Silica-rich volcanic breccia composed mainly of microcrystalline quartz/chalcedony (SiO₂), with iron-oxide staining and possible feldspar
igneous
Porphyritic Igneous Rock / Rhyolite Porphyry
Porphyritic volcanic rock
igneous
Basalt with Quartz Vein
Mafic Igneous Rock (SiO2 filling)
igneous
Obsidian
Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)
igneous
Basalt River Stone
Basalt (Mafic volcanic rock)
igneous
Pumice
Pumice (a highly vesicular volcanic rock)
igneous
Basalt
Basalt (Mafic volcanic rock)
igneous
Pumice
Pumice (a volcanic glass, primarily SiO2 with Al2O3)
igneous
River Cobble (likely Metasedimentary or Basalt)
Metamorphosed Siltstone or Altered Fine-grained Igneous Rock
metamorphic
Snowflake Obsidian
Vitreous volcanic silicate rock (SiO2) with Spherulite inclusions
igneous
Basalt
Mafic extrusive igneous rock
igneous
Mahogany Obsidian
Volcanic Glass (with inclusions of Magnetite or Hematite)
igneous
Porphyritic Basalt or Porphyritic Andesite
Porphyritic Igneous Rock
igneous
Basalt
Extrusive Igneous Rock
igneous
Quartz Vein in Host Rock
Silicon Dioxide (SiO2) in matrix
mineral/igneous
Agate
Silicon Dioxide (Chalcedony), SiO2
sedimentary
Mica (Biotite or Phlogopite variety)
Phyllosilicate (complex mineral formula involving K, Mg, Fe, Al, Si, and O)
mineral
Apache Tears (Obsidian)
Volcanic Glass (SiO2 - Silicon Dioxide with impurities)
igneous
Apache Tear
Obsidian (Hydrated Silica Rich Volcanic Glass)
igneous
Apache Tear
Obsidian (Hydrated Volcanic Glass) - SiO2 (with impurities)
igneous
Rounded dark-gray pebble, likely basalt or andesite
Fine-grained mafic to intermediate volcanic rock; commonly plagioclase ± pyroxene, amphibole, and minor olivine
igneous
Carnelian
Carnelian (Silicon Dioxide - SiO2)
mineral
Obsidian
Obsidian (Volcanic Glass, primarily SiO2)
igneous
Olivine in Basalt matrix
Peridotite (Mg, Fe)2SiO4
igneous
Leopard Skin Jasper
Orbicular Jasper (Silicon Dioxide, SiO2)
sedimentary
Beach Pebble (Basalt / Volcanic Rock)
Aphanitic Igneous Rock / Basalt
igneous
Basalt
Extrusive Igneous Rock
igneous
Pumice or Vesicular Basalt/Scoria (water-worn)
Vesicular volcanic rock
igneous