Porphyritic Andesite (often called Chinese Writing Stone)
Porphyritic Basaltic Andesite with Feldspar Phenocrysts
Category
Browse igneous (anthropogenic) specimens identified by the Rock Identifier community.
Porphyritic Andesite (often called Chinese Writing Stone)
Porphyritic Basaltic Andesite with Feldspar Phenocrysts
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
Obsidian
Obsidian (principally SiO2 + MgO, Fe3O4)
Obsidian
Obsidian (Volcanic Glass), primarily SiO2
Basalt
Mafic extrusive volcanic rock (composed primarily of Plagioclase feldspar and Pyroxene)
Black Obsidian
Volcanic Glass (predominantly SiO2)
Granite
Phaneritic plutonic rock (primarily Quartz, Feldspar, and Mica)
Basalt Pebble
Vesicular Basalt
Pumice
Pumice (a highly vesicular volcanic glass)
Andesite
Andesite (Intermediate Extrusive Volcanic Rock)
Pumice
Pumice (Vitreous volcanic rock)
Porphyry
Porphyritic Rhyolite or Andesite
Mahogany Obsidian
Obsidian (SiO2 + Fe2O3)
Granite
Granitoid
Quartz Vein Rock
Quartz (Silicon Dioxide, SiO2)
Basalt with Amygdules
Amygdaloidal Basalt
Polished Basalt
Basalt (Mafic volcanic rock)
Amygdaloidal Basalt with Agate/Chalcedony Infills
Amygdaloidal Basalt (Composition: SiO2 and (Mg,Fe)2SiO4 in matrix; SiO2 in amygdule)
Obsidian
Volcanic Glass (SiO2)
Amygdaloidal Basalt
Amygdaloidal Basalt (Mafic volcanic rock including secondary mineral infills)
Vesicular Basalt (or Scoraceous Basalt)
Basalt with vesicular texture
Granite
Granite (Felsic Plutonic Rock)
Vesicular Basalt (or Scoria)
Vesicular Basalt
Pumice
Pumice (a highly vesicular volcanic glass)
Scoria
Vesicular Basalt / Scoria
Obsidian
Volcanic Glass (Primary composition: SiO2 - Silicon Dioxide)
Yooperlite (Syenite clast containing fluorescent Sodalite)
Sodalite-bearing Syenite
Granite Pebble
Granite; primarily composed of Quartz (SiO2), Feldspar (KAlSi3O8), and Mica
Obsidian
Volcanic Glass (Amorphous Silicon Dioxide , SiO2)
Red Granite
Granite (Felsic Plutonic Rock)
Basalt
Mafic Volcanic Basalt (Major minerals: Plagioclase feldspar, Pyroxene; Minor: Olivine, Magnetite)
Granite
Granite (Mainly Quartz, Feldspar, and Mica)
Porphyritic Basalt or Andesite
Porphyritic Basalt / Andesite
Diabase (Greenstone)
Diabase or Dolerite
Granitic Pegmatite with Tourmaline and Sphalerite
Pegmatite containing Schorl (NaFe3Al6(BO3)3Si6O18(OH)4) and Sphalerite ((Zn,Fe)S)
Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
Obsidian
Obsidian (volcanic glass)
Granite
Phaneritic plutonic rock (SiO2 range 70-75%)
Peridotite (with Olivine)
Peridotite (rich in Olivine, (Mg,Fe)2SiO4)
Basalt with Magnetite
Crystalline Basalt (Primarily Plagioclase and Pyroxene) with Magnetite (Fe3O4)
Porphyritic Basalt (Flowerstone)
Porphyritic Basalt (Mafic volcanic rock)
Basalt
Basalt