Mahogany Obsidian
Volcanic Glass (SiO2 + Fe2O3)
Category
Browse igneous or sedimentary specimens identified by the Rock Identifier community.
Mahogany Obsidian
Volcanic Glass (SiO2 + Fe2O3)
Granite
Granite (Alkali-feldspar, Quartz, and Plagioclase composition)
Granite Tile (Commercial Granite)
Granite (Phaneritic Quartz-Feldspar Plutonic Rock)
Banded Rhyolite (likely Green Jasper/Agate variety)
Silicon Dioxide (SiO2) with mineral inclusions
Basalt with Olivine Phenocrysts
Porphyritic Basalt (containing Mg2SiO4 - Fe2SiO4)
Flowerstone (Porphyry)
Porphyritic Andesite or Basalt
Obsidian
Volcanic Glass (predominantly SiO2)
Basalt
Basalt (Mafic volcanic rock)
Basalt
Basalt (principally composed of pyroxene and plagioclase feldspar)
Granite
Phaneritic plutonic rock (composed of Quartz, Feldspar, and Mica/Amphibole)
Pumice
Pumice (a highly vesicular volcanic rock)
Amygdaloidal Basalt
Amygdaloidal Basalt (Mafic Extrusive volcanic rock)
Diabase (Dolerite) Cobble
Diabase / Dolerite
Apache Tear
Hydrated Obsidians (Volcanic Glass)
Basalt
Basalt (composition predominately Plagioclase feldspar and Pyroxene)
Basalt (River Pebble)
Basalt (extrusive mafic rock)
Granite
Granite (Felsic Plutonic Rock)
Basalt with Epidote (Greenstone)
Amygdaloidal Basalt (Ca2(Al, Fe)3(SiO4)3(OH) inclusions)
Granite
Granite
Granite (weathered cobble)
Granite
Pumice
Pumice (Vesicular volcanic glass / Rhyolite or Trachyte)
Apache Tear (Obsidian)
Volcanic glass (SiO2 - Silicon Dioxide)
Basalt Porphyry (River Pebble)
Porphyritic Basalt
Vesicular Basalt
Basalt
Scoria (Lava Rock)
Vesicular Basalt / Scoria
Obsidian
Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)
Obsidian
Volcanic glass (high silica content based on SiO2)
Pumice
Pumice (volcanic glass formed of highly vesicular rough textured rock)
Obsidian
Volcanic Glass (SiO2)
Granodiorite with Biotite Mica
Granodiorite (containing Quartz, Plagioclase Feldspar, and Biotite Mica)
Red Jasper (Amygdaloidal Basalt with Agate)
Silicon dioxide (SiO2) in Basalt host
Basalt
Mafic volcanic rock (formula varies by mineral content: Ca-plagioclase, Pyroxene, Olivine)
Granitic Gravel Piece
Granite (Felsic Plutonic Rock / SiO2 with Al2O3, K2O, Na2O)
Basalt with Epidote/Chlorite
Amygdaloidal Basalt (SiO2 with (Ca2(Al2,Fe)(SiO4)(Si2O7)O(OH)))
Obsidian
Obsidian (Volcanic Glass, SiO2 + impurity isotopes)
Granitic Pegmatite
Granite Pegmatite (principally KAlSi3O8, SiO2, and KAl2(AlSi3O10)(OH)2)
Granite
Granite (Felsic Plutonic Rock)
Andesite
Andesite (intermediate volcanic rock)
Granite
Phaneritic Plutonic Felsic Rock
Granite
Granite (Felsic Plutonic Rock)
Vesicular Basalt (or Scoria)
Vesicular Basalt (Aphanitic-vesicular volcanic rock)
Basalt (River Pebble)
Basalt (Aphanitic Mafic Volcanic Rock)