Bituminous Coal
Coal (Sedimentary Rock)
sedimentary
Category
Industrial Byproduct
Browse industrial byproduct specimens identified by the Rock Identifier community.
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Wollastonite
Calcium Inosilicate, CaSiO3
mineral
Chert Nodule (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Iron Meteorite (Oxidized)
Iron-Nickel Alloy (Fe, Ni)
meteorite
Bog Iron (Limonite Concretion)
Limonite (FeO(OH)·nH2O)
sedimentary
Oolitic Ironstone
Sedimentary Ooidal Ironstone (Limonite/Hematite mixture)
sedimentary
Tumbled Stone Collection (featuring Tiger's Eye, Rose Quartz, and Moss Agate)
Mixed Silicates and Oxides (predominantly SiO2 group minerals)
mineral
Talc (Soapstone variety)
Talc (Hydrated magnesium silicate) - Mg3Si4O10(OH)2
mineral
Anthracite Coal
Anthracite (Carbon-rich metamorphic coal)
metamorphic
Possible basalt or industrial iron-rich slag
Basalt (plagioclase–pyroxene rock); identification uncertain from image
igneous
Rounded river pebble
Indeterminate lithic clast; likely weathered sandstone or quartz-rich sedimentary rock
sedimentary
Unidentified dark pebble
Undetermined; possibly polished basalt, chert, or iron-rich stone
mineral
Orange fire opal jewelry
Precious opal, hydrated amorphous silica (SiO₂·nH₂O)
gemstone
Agate
Silicon Dioxide (Chalcedony), SiO2
sedimentary
Quartz Pebble
Silicon Dioxide (SiO2)
sedimentary
Quartz pebble
Silicon dioxide (SiO2)
mineral
Corundum (Sapphire / Raw Sapphire)
Aluminum Oxide (Al2O3)
gemstone
Almandine Garnet
Almandine, Fe3Al2(SiO4)3
mineral
Quartz with Tourmaline
Silicon Dioxide with Schorl (SiO2 + NaFe3Al6(Si6O18)(BO3)3(OH)4)
mineral
Gold Nugget
Gold (Au)
mineral
Sandstone (Pebble)
Sandstone (SiO2 with iron oxide impurities)
sedimentary
Gold-bearing Quartz Ore
Auriferous Quartz (SiO2 + Au)
metamorphic
Quartz and Iron Oxide
Quartz (Silicon Dioxide, SiO2) with possible Limonite/Hematite inclusions
mineral
Quartzite River Stone
Quartzite (SiO2)
metamorphic
Greenschist
Chlorite schist
metamorphic
Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Quartzite Pebble
Metamorphosed Quartz Sandstone (SiO2)
metamorphic
Soapstone (Steatite) and Quartz mix
Steatite (Mg3Si4O10(OH)2) and Quartz (SiO2)
metamorphic
Sandstone
Arenite (composed mainly of SiO2)
sedimentary
Sandstone (Iron-stained)
Arenite (primarily SiO2 with Fe2O3 staining)
sedimentary
Quartz Pebble
Crystalline Silica (SiO2)
sedimentary
Sea Shell Fragment (Calcium Carbonate)
Aragonite / Calcite (CaCO3)
mineral
Sandstone (Quartz-rich)
Arenite (primarily SiO2)
sedimentary
Diamond or Cubic Zirconia
Carbon (diamond) or Zirconium dioxide (cubic zirconia)
gemstone
Red Sandstone
Arenite (SiO2 with Fe2O3)
sedimentary
Peridotite (Olivine/Peridot)
Peridotite (comprising (Mg,Fe)2SiO4)
igneous
Pet Rock (Man-made Quartzite or Granite Cobble)
Silicon dioxide (SiO2) mixture; commonly composed of Quartz, Feldspar, and Mica
igneous or metamorphic (base stone); anthropogenic (decoration)
Garnet (Almandine)
Almandine Fe3Al2(SiO4)3
mineral
Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Granitic Gravel
Granite (Quartz, Feldspar, and Mica mixture)
igneous
Garnet Schist
Almandine-mica schist
metamorphic