Agate
Agate (Cryptocrystalline Variety of Quartz, SiO2)
Category
Browse igneous rock (volcanic glass) specimens identified by the Rock Identifier community.
Agate
Agate (Cryptocrystalline Variety of Quartz, SiO2)
Milky Quartz Pebble
Quartz (Silicon Dioxide, SiO2)
Quartz Vein in Host Rock
Silicon Dioxide (SiO2)
Quartz (Milky/Smoky variety on matrix)
Silicon Dioxide (SiO2)
Quartz (Milky or Common Quartz)
Silicon Dioxide (SiO2)
Red Jasper
Silicon Dioxide (SiO2) with Hematite (Fe2O3) inclusions
Mahogany Obsidian
Obsidian (volcanic glass with Hematite/Magnetite inclusions)
Milky Quartz
Quartz (Silicon Dioxide - SiO2)
Chalcedony (Botryoidal)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
Red Jasper
Jasper (Silicon Dioxide, SiO2 with Iron Oxide impurities)
Milky Quartz
Silicon Dioxide (SiO2)
Amethyst
Amethyst (Silicon Dioxide - SiO2 with Iron impurities)
Amethyst
Silicon Dioxide with iron impurities (SiO2)
Pink Granite
Granite (Phaneritic Quartz-Feldspar Rock)
Clear Quartz (Crystal Quartz)
Silicon Dioxide (SiO2)
Quartz Pebble (with probable inclusions or staining)
Quartz (Silicon Dioxide - SiO2)
Obsidian
Volcanic Glass (predominantly SiO2, approximately 70% or more)
Granite
Granite (Phaneritic Igneous Rock / Quartz, Feldspar, Mica)
Mahogany Obsidian
Obsidian (Volcanic Glass) with Hematite or Magnetite inclusions, SiO2 (Silicon Dioxide)
Obsidian
Obsidian (volcanic glass), primarily SiO2 (silicon dioxide)
Coarse-grained Quartz with Feldspar inclusions
Crystalline Quartz (SiO2) with Orthoclase/Plagioclase Feldspar inclusions
Obsidian
Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)
Slag
Ferrous Slag (Siliceous industrial waste)
Veined Pebble (likely a Quartz-Veined Pebble)
Pebble with Mineral Vein (e.g., Quartz Vein in a Chert/Mudstone Pebble)
Red Jasper
Silicon Dioxide (SiO2) with Hematite (Fe2O3)
Red Jasper
Red Jasper (SiO2 with Fe2O3 impurities)
Smoky Quartz (Tumbled)
Silicon Dioxide (SiO2)
Clear Quartz (Rock Crystal)
Silicon Dioxide (SiO2)
Granitic Pegmatite
Coarse-grained Granite (KAlSi3O8 + SiO2)
Quartz Geode/Druzy Quartz
Quartz (SiO₂)
Yellow Quartz Pebble
Silicon Dioxide (SiO2)
Clear Quartz Crystal
Quartz (Silicon Dioxide, SiO2)
Jasper (specifically a banded or dark variety)
Silicon Dioxide (SiO2) with impurities
Tektite (Indochinite)
Tektite (Amorphous silica-rich impact glass)
Quartz (Rock Crystal)
Quartz (SiO₂ - Silicon Dioxide)
Quartz / Vein Quartz
Quartz (Silicon Dioxide, SiO2)
Clear Quartz (Rock Crystal)
Silicon Dioxide (SiO2)
Quartz (Rock Crystal)
Silicon Dioxide (SiO2)
Pink Granite
Phaneritic Felsic Intrusive Igneous Rock
Red Jasper
Silicon dioxide (SiO2) with iron oxide (Fe2O3) inclusions
Granite
Phaneritic Igneous Rock (primarily Quartz, Feldspar, and Mica)