Coal (Anthracite)
Anthracite (Metamorphosed Coal)
Category
Browse sedimentary like (industrial composite) specimens identified by the Rock Identifier community.
Coal (Anthracite)
Anthracite (Metamorphosed Coal)
Garnet Schist
Almandine Garnet in Mica Schist (Fe3Al2(SiO4)3)
Red Sandstone (Old Red Sandstone Pebble)
Arenite with iron oxide (Fe2O3) cement
Green Fluorite (likely synthetic or heat-treated for jewelry)
Calcium Fluoride (CaF2)
Sandstone Beach Pebble
Clastic Sedimentary Rock (primarily Quartz with Iron Oxide coating)
Satin Spar (Selenite Gypsum Sphere)
Gypsum (Calcium Sulfate Dihydrate) - CaSO4·2H2O
Raw Emerald
Beryl (Be3Al2(SiO3)6) with Cr/V impurities
Chert (Nodule)
Chert (Alpha-Quartz, SiO2)
Chalcedony (Common Agate)
Cryptocrystalline Quartz (SiO2)
Yellow Jasper
Jasper (Silicon Dioxide with Iron Hydroxide impurities, SiO2 + FeO(OH))
Chert (specifically Flint or Jasper variant)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Quartz Geode
Silicon dioxide (SiO2)
Concrete
Anthropogenic Sedimentary Conglomerate (Cement mixture: typically Ca2SiO4, Ca3SiO5, Ca3Al2O6)
Jasper, Agate, Quartz Mix (Polished Beads)
SiO₂ (Silicon Dioxide) for Quartz. Jasper and Agate are cryptocrystalline varieties of Quartz.
Polished Chert (Flint)
Silicon Dioxide (SiO2)
Polished dragon blood jasper
Jasper, a microcrystalline variety of quartz (SiO₂), colored by iron oxides and other inclusions
Chert (Chalcedony/Agate variety)
Microcrystalline Quartz (SiO2)
Quartz Geode with Calcite
Silicon Dioxide (SiO2) with Calcium Carbonate (CaCO3)
Iridescent opal-like specimen
Likely common opal (hydrated amorphous silica, SiO₂·nH₂O), possibly treated or synthetic
Chert (often called Flint)
Chert (Silicon Dioxide, SiO2)
Chert (Jasper variety)
Silicon Dioxide (SiO2)
Magnetite (Lodestone)
Magnetite (Fe3O4)
Tumbled orbicular/patterned jasper (likely brecciated jasper)
Microcrystalline quartz (SiO₂) with iron-oxide and possibly calcite/chalcedony veining
Banded Iron Formation (BIF) / Red Jasper with Hematite
Ferruginous Chert (primarily Quartz [SiO2] and Hematite [Fe2O3])
Limestone
Sedimentary Calcium Carbonate (CaCO3)
Quartz (Sunstone-like Chalcedony)
Silicon Dioxide (SiO2)
Slag Glass (Cullet)
Amorphous Silica / Glass residue
Botryoidal Pyrite
Iron Sulfide (FeS2)
Chert (Jasper variety)
Microcrystalline Quartz (SiO2)
Chert (specifically Flint or Dark Chert)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Kyanite
Kyanite (Al2SiO5)
Quartz Druzy (on Calcedony/Quartz base)
Silicon Dioxide (SiO2)
Ferro-slag (Leland Blue/Slag Glass)
Anthropogenic Vitreous Silica (Industrial Slag)
Banded Chert (Flint/Jasper variety)
Microcrystalline Quartz (SiO2)
Copper-bearing rock, likely native copper in matrix
Native copper (Cu), possibly with cuprite/iron-rich matrix
Red Sandstone
Arenite (Iron-rich Sandstone)
Chert (varieties: Flint or Chalcedony)
Microcrystalline silica (SiO2)
Chert (Arrowhead variety)
Chert (SiO2)
Garnet Schist
Garnetiferous Micaceous Schist
Chert (Green Chert/Jasper)
Chert (primarily Microcrystalline Quartz, SiO2)
Red jasper (likely iron-rich chert)
Microcrystalline quartz (SiO₂) colored by hematite/goethite
Pegmatite
Igneous Pegmatite