Common Opal
Hydrated Amorphous Silica (SiO2·nH2O)
Category
Browse mineral, often found as detrital grains in sedimentary rocks specimens identified by the Rock Identifier community.
Common Opal
Hydrated Amorphous Silica (SiO2·nH2O)
Blue Chalcedony
Silicon Dioxide (SiO2)
Quartzite
Quartzite (primarily SiO2)
Agate (or Chalcedony)
SiO2 (Silicon Dioxide) - a cryptocrystalline variety of quartz
Quartz (various varieties)
SiO₂ (Silicon Dioxide)
Calcite (likely a tumbled specimen)
Calcite (CaCO 3 )
Olivine Basalt
Mafic Volcanic Rock (rich in (Mg, Fe)2SiO4)
Sandstone
Arenite (SiO2 primarily)
Quartzite
Quartzite (SiO2)
Garnet Schist
Almandine Garnet in Mica Schist (Fe3Al2(SiO4)3)
Petrified Wood
Silicified Wood (SiO2)
Quartz Geode
Silicon Dioxide (SiO2)
Chalcedony
Chalcedony (SiO₂)
Chert (Tan/Grey variety)
Microcrystalline or cryptocrystalline Quartz (SiO2)
Chert (Flint)
Silicon Dioxide (SiO2)
Green Fluorite
Fluorite (Calcium Fluoride, CaF2)
Basalt River Stone
Basalt (Aphanitic Mafic Igneous Rock)
Basalt
Mafic Volcanic Rock (Primarily Plagioclase Feldspar and Pyroxene)
Jasper with Quartz inclusion
Silicon Dioxide (SiO2) - Microcrystalline Quartz
Zebra Stone (Banded Chert or Limestone)
Silicon Dioxide (SiO2) with Calcium Carbonate (CaCO3) inclusions
Fossil Shell in Sedimentary Matrix
Bivalvia (fossil) in Calcium Carbonate Matrix
Flesh-toned Siltstone
Siltstone (composed of microscopic Quartz and Feldspar grains)
Yellow Quartzite (Yellow Jasper)
Silicon Dioxide (SiO2)
Clear Quartz (Rock Crystal)
Silicon Dioxide (SiO2)
Clear Quartz
Quartz (Silicon Dioxide, SiO2)
Petrified Wood
Silicified Wood (primarily SiO₂ / Silicon Dioxide)
Granite Thin Section
Granitic rock (Phaneritic texture)
Sandstone
Arenite (composed primarily of SiO2)
Olivine (Peridot)
Magnesium Iron Silicate (Mg, Fe)2SiO4
Lepidolite
Lepidolite [K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2]
Limestone
Calcium carbonate (CaCO3)
Gneiss
Gneiss (pronounced 'nice')
Yellow Quartzite
Quartzite (SiO2)
Quartzite
Quartzite (composed primarily of SiO2)
Epidote
Epidote ({Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH))
Quartzite
Quartzite (SiO2)
Nickel coin (U.S. currency)
Cupronickel (75% Copper, 25% Nickel alloy)
Banded Iron Formation
Banded Iron Formation (BIF)
Quartz
Silicon Dioxide (SiO2)
Amazonite
K(AlSi3O8), Microcline (potassium feldspar)
Granite (Pink/Potassium-rich)
Pink Granite (contains K-Feldspar, Quartz, and Plagioclase)
Limestone (Fossiliferous)
Calcium Carbonate (CaCO3) - Bioclastic Limestone