Hematite
Iron(III) oxide (Fe2O3)
Category
Browse mineral precipitate (anthropogenic context) specimens identified by the Rock Identifier community.
Hematite
Iron(III) oxide (Fe2O3)
Hematite Nodular Iron Ore
Hematite (Fe2O3)
Hematite
Iron(III) oxide (Fe2O3)
Geode
Crystalline Quartz (SiO2) within a nodule
Polished basalt pebble
Basalt, primarily plagioclase feldspar, pyroxene, and iron-titanium oxides
Fluorite (Blue)
Calcium Fluoride (CaF2)
Agate (specifically crazy lace agate / orbicular agate node)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
Moss Agate
Silicon Dioxide with inclusions (SiO2)
Limonite/Ironstone
Limonite (Hydrous ferric oxides), FeO(OH)·nH2O
Anthracite Coal
Anthracite (high-rank coal)
Quartz Vein Rock
Silicon Dioxide (SiO2)
Jasper
Silicon Dioxide (Quartz variety, SiO2)
Turquoise
Turquoise (CuAl6(PO4)4(OH)8·4H2O)
Ferruginous Quartz
Silicon Dioxide (SiO2) with Hematite/Limonite inclusions
Bloodstone
Heliotrope (Cryptocrystalline Quartz, SiO2)
Chalcedony (Agate/Carnelian)
Cryptocrystalline Silicon Dioxide (SiO2)
Flint or chert flake
Microcrystalline quartz (SiO₂), commonly chalcedony with possible impurities
Quartz Geode
Silicon Dioxide (SiO2)
Blue Chalcedony
Silicon Dioxide (SiO2)
Basalt (Crushed Stone)
Basalt (Mafic Extrusive Igneous Rock)
Yellow Calcite
Calcium Carbonate (CaCO3)
Hematite with Magnetite
Iron Oxide (Fe2O3)
Manganese Ore (Psilomelane/Pyrolusite)
Psilomelane ((Ba,H2O)2Mn5O10) and Pyrolusite (MnO2)
Fossilized Dinosaur Skull (Tyrannosaurus rex)
Tyrannosaurus rex (permineralized fossil), rich in Hydroxylapatite/Silica
Orange Calcite (with White Calcite/Quartz matrix)
Calcium Carbonate (CaCO3)
Quartz-veined Basalt or Limestone Pebble
Quartz vein in host rock (Silicate mineral in carbonate or volcanic matrix)
Yellow Jasper
Jasper (Silicon Dioxide, SiO2)
Jasper (Red Jasper)
Silicon Dioxide (SiO₂)
Chert (Nodule)
Cryptocrystalline Silica (SiO2)
Blue-gray botryoidal mineral specimen
Likely botryoidal chalcedony or hemimorphite; species cannot be confirmed from the image alone
Quartz on Schist
Silicon Dioxide (SiO2) on Foliated Metamorphic Rock
Quartz (possibly milky quartz)
Quartz (Silica; SiO₂)
Quartz Geode
Silicon Dioxide (SiO2)
Limonite (Yellow Ochre)
Limonite (an amorphous mixture of hydrated iron oxides, primarily FeO(OH)·nH2O)
Green Calcite
Calcium Carbonate (CaCO3)
Quartz Crystal on Matrix
Silicon Dioxide (SiO2)
Blue Chalcedony
Cryptocrystalline Quartz (SiO2)
Celestine (Celestite)
Strontium sulfate (SrSO4)
Caribbean Calcite
Calcium Carbonate (CaCO3) with Aragonite
Amethyst Geode
Silicon Dioxide with impurities (SiO2)
Amethyst
Silicon Dioxide (SiO2)
Quartz Vein Rock
Silicon Dioxide (SiO2)