Hematite
Iron(III) oxide (Fe2O3)
Category
Browse mineral or sedimentary (if chert) specimens identified by the Rock Identifier community.
Hematite
Iron(III) oxide (Fe2O3)
Pyrite in Matrix (likely Quartz or Schist matrix)
Iron Sulfide (FeS2)
Satin Spar (Selenite)
Gypsum (Calcium Sulfate Dihydrate) - CaSO4·2H2O
Agate
Silicon Dioxide (SiO2) - variety: Chalcedony
Banded Agate (specifically Carnelian Agate slice)
Chalcedony (cryptocrystalline variety of Quartz), SiO2
Orange Calcite
Calcium Carbonate (CaCO3)
Pyrite (Fool's Gold)
Iron Sulfide (FeS2)
Blue Caribbean Calite
Calcium Carbonate (CaCO3) with trace Aragonite
Fancy Jasper
Silicon Dioxide (SiO2) with impurities
Blue Calcite
Calcium Carbonate (CaCO3)
Chalcedony (Moonstone variant or White Agate)
Silicon Dioxide (SiO₂)
Quartz Geode Fragment
Silicon Dioxide (SiO2)
Magnetite Orthorthotropic Rock
Magnetite (Fe3O4)
Carnelian Agate
Chalcedony (SiO2) with iron oxide inclusions
Tree Agate
Dendritic Chalcedony (SiO2)
Gneiss
Gneiss
Clay (as a rock-forming material)
Clay minerals (e.g., Kaolinite group, Smectite group, Illite group, Chlorite group)
Pink Opal
Hydrated silica (SiO2 "n H2O)
Quartz (Small Fragment)
Silicon Dioxide (SiO2)
Turquoise
CuAl6(PO4)4(OH)8·4H2O (Hydrated copper and aluminium phosphate)
Quartz
Silicon Dioxide (SiO2)
Turquoise
Hydrous phosphate of copper and aluminium (CuAl6(PO4)4(OH)8·4H2O)
White Chalcedony (likely Common Opal or Milky Quartz)
Silicon Dioxide (SiO2)
Turquoise (likely Sleeping Beauty variety or treated Howlite imitation)
Hydrated phosphate of copper and aluminium, CuAl6(PO4)4(OH)8·4H2O
Howlite
Calcium Borosilicate Hydroxide (Ca2B5SiO9(OH)5)
Fluorite
Calcium fluoride (CaF2)
Sandstone
Clastic sedimentary rock (primarily SiO2)
Quartzite river stone
Quartzite (SiO2)
Shale
Fissile mudrock (composed primarily of clay minerals and quartz)
Geode (Unopened)
Silica Concretion / Geode (Formula: SiO2 for quartz internal contents)
Sandstone with Iron Concretion
Arenite with Limonite/Goethite Concretion
Sandstone (Quartzose)
Arenite (primarily SiO2)
Blue Lace Agate (Chert/Chalcedony)
Silicon dioxide (SiO2)
Limonite (Iron Ore)
Limonite (̑FeO(OH)·nH₂O)
Sandstone
Arenite (SiO2 principal)
Sandstone (Banded)
Clastic Sedimentary Rock (primarily SiO2)
Sandstone (Banded)
Clastic sedimentary rock (primarily SiO2)
Quartz Geode
Silicon Dioxide (SiO2)
Quartz (Milky or Clear fragment)
Silicon Dioxide (SiO2)
Quartz Crystal Fragment
Quartz (Silicon Dioxide, SiO2)
Quartz (Milky/Crystalline fragment)
Silicon Dioxide (SiO2)
Quartz Geode
Crystalline Silicon Dioxide (SiO2) in sedimentary/volcanic host