Granite Gneiss
Gneiss (derived from granitic protolith)
Category
Browse industrial byproduct (often confused with igneous rocks or meteorites) specimens identified by the Rock Identifier community.
Granite Gneiss
Gneiss (derived from granitic protolith)
Smoky Quartz
SiO2 (Silicon Dioxide)
Banded Agate (specifically Botryoidal/Orbicular Agate)
Silicon Dioxide (SiO2)
Milky Quartz
Silicon Dioxide (SiO2)
Blue-dyed Quartz Druzy
Silicon Dioxide (SiO2) with artificial pigment
Milk Quartz (River Pebble)
Quartz (Silicon Dioxide, SiO2)
Citrine Quartz
Crystalline Silicon Dioxide (SiO2) with Ferric Iron impurities
Diamond
Diamond (a metastable allotrope of carbon, C)
Banded Gneiss (River Rock/Pebble)
Gneiss (specifically a banded variety often found as a river rock)
Pumice
Pumice (volcanic rock)
Amazonite
Amazonite (KAlSi3O8 - a variety of Microcline Feldspar)
Prehnite with Epidote inclusions
Prehnite: Ca2Al(AlSi3O10)(OH)2; Epidote: Ca2(Al,Fe)3(SiO4)3(OH)
Granite
Granite (a plutonic igneous rock)
Banded Gneiss (River Cobble)
Gneiss (a high-grade metamorphic rock)
Gneiss
Gneiss (High-grade metamorphic rock typically composed of Quartz, Feldspar, and Mica/Amphibole)
Calcite
Calcite (CaCO₃, Calcium Carbonate)
Gneiss
Gneiss (High-grade regional metamorphic rock)
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
Talc
Talc (Mg₃Si₄O₁₀(OH)₂)
Chrome Diopside
Magnesium Calcium Silicate (MgCaSi2O6) containing Chromium impurities
Carnelian Agate
Silicon Dioxide (SiO2) - Variety: Chalcedony
Banded Gneiss
Gneiss (Metamorphic high-grade rock)
Quartz Geode (Nodule)
Silicon Dioxide (SiO2)
Gold Ore in Quartz/Schist
Auriferous Quartz and Sulfide-bearing Schist
Pumice
Pumicite (fine-grained pumice), Scoria (similar origin but denser and darker, usually basaltic)
Amethyst
SiO2 (Silicon Dioxide)
River Pebble (Basalt/Greywacke)
Weathered Basalt or Fine-Grained Greywacke
Yellow Chalcedony
Chalcedony (a cryptocrystalline variety of Quartz, SiO₂)
Rose Quartz
Rose Quartz (SiO2)
Muscovite Mica
Muscovite (KAl₂(AlSi₃O₁₀)(F,OH)₂))
Amethyst
Silicon Dioxide (SiO2) with iron impurities
Soapstone
Steatite (composed primarily of Talc: Mg3Si4O10(OH)2)
Banded Gneiss
Gneiss (Metamorphic high-grade rock)
Green Tourmaline (Verdelite)
Tourmaline Group; often Elbaite (Na(Li,Al)3Al6(BO3)3Si6O18(OH)4) or Dravite (NaMg3Al6(BO3)3Si6O18(OH)4)
Smoky Quartz
Smoky Quartz (SiO ₂)
Hematite
Iron(III) oxide (Fe2O3)
Basalt
Basalt (a mafic extrusive igneous rock)
Quartz (likely tumbled or naturally water-worn)
Quartz (SiO₂ - Silicon Dioxide)
Coal (most likely Bituminous or Anthracite)
Bituminous Coal (Grade of Coal), Anthracite (Grade of Coal)
Quartz
Silicon Dioxide (SiO2)
Obsidian
Volcanic glass
Gneiss (specifically Biotite Gneiss)
Gneiss (high-grade metamorphic rock primarily composed of Silicates)