Devil's Toenail (Fossil Oyster)
Gryphaea arcuata (Calcium Carbonate, CaCO3)
sedimentary
Category
Mineral (Evaporite)
Browse mineral (evaporite) specimens identified by the Rock Identifier community.
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Serpentinite
Serpentine-group minerals, chiefly antigorite, lizardite, and chrysotile; approximate formula Mg3Si2O5(OH)4
metamorphic
Small pale mineral fragment
Unidentified; possibly quartz, calcite, or feldspar
mineral
Proustite
Proustite (Ag3AsS3)
mineral
Limonite Ironstone
Goethite-Limonite concretion / Iron oxide
sedimentary
Milky quartz (rough quartz crystal)
Quartz, silicon dioxide (SiO₂)
mineral
Pebble with vesicles, likely basalt
Vesicular basalt; chiefly plagioclase, pyroxene, and iron-magnesium minerals
igneous
Epidote
Epidote (Ca2(Al2,Fe3+)AlSi3O12(OH))
mineral
Tiger's Eye
Quartz pseudomorph after crocidolite (SiO2)
gemstone
Granitic Pegmatite with Schorl Tourmaline
Granitic Pegmatite (Schorl: NaFe3Al6(BO3)3Si6O18(OH)4)
igneous
Banded Sandstone (Beach Pebble)
Quartz Arenite Sandstone
sedimentary
Gneiss
Gneiss (a rock type, not a specific mineral with a formula)
Metamorphic Rock
Granite
Granite (felsic intrusive igneous rock)
igneous
Druzy Quartz on Sandstone
Silicon Dioxide (SiO2) with Quartz Crystals on Clastic Sedimentary Rock
sedimentary
Tumbled agate/chalcedony
Microcrystalline quartz (SiO₂), likely mossy or dendritic agate with iron-oxide inclusions
mineral
Fluorite
Calcium Fluoride (CaF2)
mineral
Talc Schist / Soapstone
Talc (Mg3Si4O10(OH)2)
metamorphic
Quartz Druze on Matrix
Silicon Dioxide (SiO2)
mineral
Limonite/Goethite (Iron Ore)
Hydrous ferric oxides (FeO(OH)·nH2O)
mineral
Limonite (Iron Ore)
FeO(OH)·nH2O (Hydrated iron(III) oxide-hydroxide mixture)
mineral
Iron Ore (Limonite and Hematite)
Goethite/Limonite (FeO(OH)·nH2O) and Hematite (Fe2O3)
mineral
Quartz in Greenstone
Metamorphic rock with quartz vein (SiO2 / mixed silicates)
metamorphic
Blue Apatite
Apatite - Ca5(PO4)3(F,Cl,OH) (Calcium phosphate with Fluorine, Chlorine, or Hydroxyl)
mineral
Sandstone (likely Arkosic or Lithic)
Clastic Sedimentary Rock (SiO2 with accessory minerals)
sedimentary
Turquoise and Hematite
Turquoise (CuAl6(PO4)4(OH)8·4H2O) and Hematite (Fe2O3)
mineral
Botryoidal Prehnite
Prehnite (Ca2Al(AlSi3O10)(OH)2)
mineral
Granite
Phaneritic Felsic Igneous Rock
igneous
Fossil shark tooth, likely sand tiger shark
Fossilized selachian tooth; possibly *Carcharias* or *Striatolamia*
fossil
Shark Tooth Fossil
Carcharodon / Otodus fossilized tooth (Calcium Phosphate / Hydroxyapatite)
fossil
Fossilized Shark Tooth
Chondrichthyes (Class)
fossil
Banded Gneiss
Gneiss (Foliated Metamorphic Rock)
metamorphic
Granite
Granite (composed mainly of Quartz, Potassium Feldspar, Plagioclase, and Biotite/Mica)
igneous
Gneiss (specifically Granite Gneiss)
Gneiss (High-grade Regional Metamorphic Rock)
metamorphic
Vesicular basalt
Basalt, commonly plagioclase feldspar + pyroxene ± olivine
igneous
Limonite with Pyrite
Hydrated Iron Oxide Hydroxide, FeO(OH)·nH2O
mineral
Silver Nuggets (Natural or Cast)
Native Silver (Ag)
mineral
Quartz Geode
Silicon Dioxide (SiO2) in Geodic Cavity
sedimentary
Pyrite (Fool's Gold)
Iron Sulfide (FeS2)
mineral
Cobaltian Calcite
Cobalt-bearing Calcite (Ca,Co)CO3
mineral
Black Spinel
Magnesium Aluminum Oxide (MgAl2O4)
mineral
Desert Rose
Gypsum (CaSO4 · 2H2O) or Barite (BaSO4) rosette
mineral
Quartz with Sulfide Inclusions
Silicon Dioxide (SiO2) with metallic mineral inclusions
mineral