Mahogany Obsidian
Obsidian (Volcanic Glass) with Hematite or Magnetite inclusions, SiO2 (Silicon Dioxide)
Category
Browse sedimentary and igneous (mixed) specimens identified by the Rock Identifier community.
Mahogany Obsidian
Obsidian (Volcanic Glass) with Hematite or Magnetite inclusions, SiO2 (Silicon Dioxide)
Porphyritic Rhyolite (Red Rhyolite)
Rhyolite (Porphyry)
Coarse-grained Granite (Quartz and Feldspar dominated)
Granitoid (KAlSi3O8 – NaAlSi3O3 – CaAl2Si2O8 – SiO2)
Granite
Phaneritic high-silica plutonic rock (composed primarily of Quartz, Feldspar, and Mica)
Smoky Quartz in Matrix
Silicon dioxide (SiO2) within Pegmatite/Gneiss
Granite
Granite
Snowflake Obsidian (or similar porphyritic volcanic rock)
Obsidian with Spherulites (if glassy), or Porphyritic Rhyolite/Andesite (if crystalline groundmass)
Porphyritic Rhyolite (Red Porphyry)
Porphyritic Rhyolite (Felsic volcanic rock)
Basalt
Basalt (Mafic volcanic rock)
Obsidian
Volcanic Glass (SiO2, usually >70% silica content)
Basalt
Basalt (extrusive igneous rock)
Porphyritic Basalt
Porphyritic Basalt (with plagioclase phenocrysts)
Granite
Granite (Felsic intrusive igneous rock)
Basalt
Basalt
Black Obsidian
Volcanic Glass (predominantly SiO2, Silicon Dioxide)
Granite
Granite (composed primarily of Quartz (SiO2), Alkali Feldspar, and Plagioclase)
Obsidian
Volcanic glass (Mainly SiO2)
Iron-Nickel Meteorite (Possible Chondrite or Oxidized Iron)
Siderite (Nickel-Iron) or Chondrite (Si/Fe composite)
Snowflake Obsidian
Volcanic glass with Cristobalite inclusions (70–75% SiO2)
Clear Quartz (Rock Crystal)
Silicon Dioxide (SiO2)
Larvikite
Monzonite (intermediate intrusive igneous rock containing plagioclase, alkali feldspar, augite, and biotite)
Obsidian (Apache Tear)
Obsidian (Amorphous Volcanic Glass / SiO2 with impurities)
Amygdaloidal Basalt
Amygdaloidal Basalt (Mafic volcanic rock)
Apache Tear (Obsidian)
Obsidian (Hydrated Amorphous Silica, SiO2 + MgO/Fe3O4)
BROWN GRANITE (likely 'Tan Brown' or similar)
Granite (specifically a variety rich in orthoclase feldspar, often with biotite and possibly hornblende)
Granite
Granite (felsic intrusive igneous rock)
Pumice
Pumicite (fine-grained pumice), Scoria (similar origin but denser and darker, usually basaltic)
Obsidian
Obsidian (volcanic glass), predominantly amorphous SiO₂
Granite Pebble
Granite (a phaneritic intrusive igneous rock consisting of quartz, alkali feldspar, and plagioclase)
Granite
Granite
Basalt
Basalt (a mafic extrusive igneous rock)
Granite
Granite (a common rock type, not a single mineral with a formula. Composed primarily of quartz, feldspar, and mica/amphibole).
Andesite
Andesite
Porphyritic Andesite
Andesite
Amygdaloidal Basalt with Secondary Minerals
Basalt containing secondary mineralization (likely Chlorite, Celadonite, or Zeolites)
Granite
Granite (a plutonic igneous rock)
Basalt
Basalt (extrusive igneous rock)
Milky Quartz
Silicon Dioxide (SiO2)
Milky Quartz with Iron Inclusions
Silicon Dioxide (SiO2)
Granite
Granite (felsic intrusive igneous rock)
K2 Azurite Granite / K2 Stone
Granite (igneous rock) with Azurite inclusions (mineral)
Granite
Granite (a plutonic igneous rock composed primarily of quartz, feldspar, and mica)