Obsidian
Volcanic Glass (Amorphous Silicon Dioxide, SiO2)
Category
Browse sedimentary and igneous (mixed) specimens identified by the Rock Identifier community.
Obsidian
Volcanic Glass (Amorphous Silicon Dioxide, SiO2)
Porphyritic Basalt
Amygdaloidal Porphyritic Basalt
Brown Antique Granite
Anorthosite (Technically a plutonic rock composed mainly of plagioclase feldspar)
Porphyritic Rhyolite (Red)
Rhyolite (Porphyry)
Granite (specifically Rapakivi Granite)
Phaneritic Felsic Igneous Rock (Granite)
Mahogany Obsidian
Volcanic Glass (SiO2 + Fe2O3)
Granite Pegmatite
Phaneritic Plutonic Igneous Rock
Apache Tear
Hydrated Obsidians (Volcanic Glass)
Pumice
Pumice (a highly vesicular amorphous volcanic glass)
Quartz Veined Basalt Pebble
Amygdaloidal Basalt with Quartz (SiO2) veining
Obsidian
Obsidian (principally SiO2)
Mahogany Obsidian
Volcanic Glass with Hematite/Magnetite inclusions
Black Tourmaline in Quartz
Schorl (NaFe3Al6(BO3)3Si6O18(OH)4) in Silicon Dioxide (SiO2)
Granite
Felsic Intrusive Igneous Rock
Granite
Phaneritic Felsic Igneous Rock (primarily Quartz, Feldspar, and Mica)
Labradorite (Dark or Black variety)
Labradorite (member of Plagioclase Feldspar group), (Na,Ca)(Si,Al)4O8
Milky Quartz
Silicon Dioxide (SiO2)
Clear Quartz (Rock Crystal)
Silicon Dioxide (SiO2)
Obsidian
Volcanic Glass (Amorphous Silicon Dioxide)
Obsidian
Obsidian (Volcanic Glass)
Obsidian
Volcanic Glass (SiO2)
Granitic Pegmatite (Muscovite and Quartz)
Pegmatite (KAl2(AlSi3O10)(OH)2 / SiO2)
Granodiorite (or Granite) Pebble
Phaneritic Felsic Igneous Pebble
Granite (Weathered River Rock)
Plutonic Igneous Rock (primarily Quartz, Feldspar, and Mica)
Kimberlite
Kimberlite (Porphyritic Peridotite)
Granite
Felsic Plutonic Rock (primarily SiO2, Al2O3, K2O, Na2O)
Porphyritic Basalt (Chinese Writing Stone)
Porphyritic Basalt with Feldspar Phenocrysts
Pink Granite
Granite (Felsic Plutonic Rock)
Obsidian
Obsidian (Volcanic Glass, primarily SiO2)
Amygdaloidal Basalt
Amygdaloidal Basalt (extrusive volcanic rock with mineral inclusions)
Granodiorite (Riverbed Cobble)
Granodiorite
Andesite Porphyry
Andesite (Intermediate Volcanic Rock)
Obsidian
Volcanic Glass (SiO2 rich)
Pumice
Felsic Volcanic Glass / Vesicular Rhyolite
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
Scoria (Volcanic Rock)
Scoria (often basaltic scoria)
Diorite (Salt and Pepper Rock)
Diorite
Obsidian (in jewelry setting)
Volcanic Glass (Amorphous Silica)
Granitic Pegmatite
Granite Pegmatite (principally KAlSi3O8, SiO2, and KAl2(AlSi3O10)(OH)2)
Scoria
Scoria (a vesicular basalt or andesite)
Apache Tear
Obsidian (Hydrated Volcanic Glass, SiO2)
Obsidian (specifically Silver Sheen Obsidian)
Volcanic Glass (approx. 70–75% SiO2 plus MgO, Fe3O4)