Satin Spar (often marketed as Selenite)
Gypsum (Calcium Sulfate Dihydrate) - CaSO4·2H2O
Category
Browse industrial byproduct (often mistaken for obsidian or mineral) specimens identified by the Rock Identifier community.
Satin Spar (often marketed as Selenite)
Gypsum (Calcium Sulfate Dihydrate) - CaSO4·2H2O
Milky Quartz with Iron Inclusions
Quartz (Silicon Dioxide, SiO2)
Garnet
Garnet Group (complex nesosilicates with general formula X3Y2(SiO4)3, where X can be Ca, Mg, Fe2+, Mn2+ and Y can be Al, Fe3+, Cr3+, V3+)
Flesh-colored Quartzite
Quartzite (SiO2)
Ruby
Corundum (Al2O3:Cr)
Ruby
Corundum (Aluminum Oxide with Chromium traces), Al2O3:Cr
Dyed Quartz (often sold as 'Blue Quartz' or 'Blue Agate')
Silicon Dioxide (SiO2) with artificial pigment
Pyrite
Iron Sulfide (FeS2)
Red Shale
Fissile Siliciclastic Sedimentary Rock
Ruby
Corundum (Al2O3 with Chromium traces)
Fluorite (Green Fluorite)
Calcium Fluoride (CaF2)
Green Fluorite
Calcium Fluoride (CaF2)
Yellow Quartzite (River Pebble)
Silicon Dioxide (Metamorphosed Sandstone), SiO2
Milky Quartz with Mineral Inclusions
Silicon Dioxide (SiO2)
Kyanite (within Quartz)
Kyanite (Al2SiO5) in crystalline Quartz base (SiO2)
Orange Calcite (likely polished specimen)
Calcite
Dyed Magnesite (often sold as Red Turquoise or Howlite)
Magnesium Carbonate (MgCO3)
Magnetite (Lodestone)
Magnetite (Fe3O4)
Banded Iron Formation (BIF) with Quartz
Banded Iron Formation, often composed of alternating layers of hematite (Fe2O3) or magnetite (Fe3O4) and chert (microcrystalline quartz, SiO2)
Green Aventurine
Aventurine (a variety of Quartz, SiO2)
Quartz (likely Milky Quartz)
Quartz (SiO₂ - Silicon Dioxide)
Schist
Mica Schist (Medium-grade Metamorphic Rock)
Schorl (Black Tourmaline) in Quartz Matrix
Schorl: NaFe3Al6(BO3)3Si6O18(OH)4 (Complex Borosilicate)
Jasper pebble
Jasper (Silicon Dioxide, SiO2)
Iolite-bearing Gneiss (Cordierite)
Cordierite (Mg2Al4Si5O18) in Gneiss matrix
Rose Quartz
Silicon Dioxide (SiO2) with trace amounts of titanium, iron, or manganese
Agate (Grey Agate Slice)
Microcrystalline Quartz (SiO2)
Quartzite with Dark Mineral Inclusions
Quartzite (primarily SiO2) with accessory minerals
Asphalt Chunk (with aggregate)
Bituminous concrete / Anthropogenic conglomerate
Ferruginous Quartz
SiO2 (Silicon Dioxide) with Iron Oxide inclusions (FeO(OH) / Fe2O3)
Amethyst
Quartz (SiO2) variety
Pyrite on Quartz (Fool's Gold in Quartz)
Iron Sulfide (FeS2) on Silicon Dioxide (SiO2)
Quartz Druze on Matrix (Geode Fragment)
Quartz (Silicon Dioxide, SiO2)
Diamond (Green tinted)
Carbon (C) with trace impurities or lattice defects
Blue Crackle Quartz (Dyed Fire Agate/Quartz)
Silicon Dioxide (SiO2) with artificial dye treatment
Stilbite
Stilbite-Ca (NaCa4Mg[Al9Si27O72]·28H2O)
Mica Schist
Crystalline Schist (often primarily Muscovite or Biotite sheet silicates)
Tourmaline (likely Schorl)
Tourmaline Group Mineral (e.g., Schorl for black varieties); (Na,Ca)(Li,Mg,Fe,Mn,Al)3Al6(BO3)3Si6O18(OH)4
Rose Quartz
Silicon Dioxide (SiO2) with trace amounts of titanium, iron, or manganese
Red Jasper
Silicon Dioxide (SiO2) - Opaque microcrystalline quartz
Quartz Geode
Silicon Dioxide (SiO2)
Green Agate
Silicon dioxide (SiO₂)