Obsidian
Obsidian (Volcanic Glass, SiO2)
Category
Browse igneous and sedimentary specimens identified by the Rock Identifier community.
Obsidian
Obsidian (Volcanic Glass, SiO2)
Vesicular Basalt (Pumice-like)
Vesicular Basalt
Obsidian
Volcanic Glass (Amorphous Silica)
Silver Sheen Obsidian
Volcanic Glass (Amorphous Silicon Dioxide - SiO2 with impurities)
Flowerstone
Porphyritic Basalt or Porphyritic Andesite
Granodiorite
Granodiorite (containing Plagioclase, Quartz, and Biotite)
Snowflake Obsidian
Volcanic Glass with Spherulitic Cristobalite (SiO2)
Basalt (River Pebble)
Basalt
Rhyolite
Rhyolite (felsic volcanic rock)
Basalt
Basalt (comprising plagioclase, pyroxene, and olivine)
Basalt with Plagioclase Phenocrysts
Porphyritic Basalt
Amygdaloidal Basalt with Secondary Minerals
Basalt containing secondary mineralization (likely Chlorite, Celadonite, or Zeolites)
Mahogany Obsidian
Volcanic Glass with Hematite/Magnetite inclusions
Pink Granite (Fragment)
Pink Granite (dominated by Potassium Feldspar: KAlSi3O8)
Granite
Phaneritic Plutonic Rock (Granite)
Mahogany Obsidian
Volcanic Glass (with inclusions of Magnetite or Hematite)
Basalt
Basalt
Obsidian (worked into an arrowhead profile)
Obsidian (volcanic glass), primarily SiO2 (Silicon Dioxide)
Smoky Quartz in Matrix
Silicon dioxide (SiO2) within Pegmatite/Gneiss
Granite
Granite (composed primarily of Quartz SiO2, Alkali Feldspar KAlSi3O8, and Plagioclase)
Granite
Granite
Black Obsidian
Volcanic Glass (Amorphous Silicon Dioxide SiO2)
Amygdaloidal Basalt
Vesicular Basalt with secondary mineral infilling (commonly Zeolite, Calcite, or Quartz)
Basalt
Basalt (containing Pyroxene, Plagioclase Feldspar, and Olivine)
Obsidian
Volcanic glass (SiO2-rich amorphous silicate)
Tumbled Obsidian
Volcanic Glass (Silicon Dioxide)
Obsidian
Volcanic Glass (Amorphous Silicon Dioxide)
Vesicular Basalt or Scoria
Basalt (extrusive volcanic rock)
Scoria (Lava Rock)
Scoria (Mafic Volcanic Rock)
Labradorite (specifically Larvikite beads)
Plagioclase Feldspar (Na,Ca)(Si,Al)4O8
Pink Granite
Granite (High K-Feldspar variety)
Black Obsidian
Volcanic Glass (SiO2 + impurities like Fe3O4)
Quartz with Tourmaline and Iron Staining
Silicon Dioxide (SiO2) with Schorl (NaFe2+3Al6(Si6O18)(BO3)3(OH)3OH)
Obsidian
Obsidian (volcanic glass, amorphous silica rich rock)
Porphyritic Basalt (Chinese Writing Stone)
Porphyritic Basalt with Feldspar Phenocrysts
Basalt with Secondary Mineral Inclusions
Amygdaloidal Basalt (Mafic volcanic rock, primarily Augite and Plagioclase)
Scoria
Vesicular Basalt / Scoriaceous Basalt
Obsidian
Amorphous volcanic glass (70-75% SiO2)
Basalt
Basalt (Aphanitic Mafic Volcanic Rock)
Porphyritic Basalt
Porphyritic Basalt (Mafic extrusive rock)
Basalt
Basalt
Granodiorite Pebble
Granodiorite