Black Spinel
Magnesium Aluminum Oxide (MgAl2O4)
mineral
Category
Mineral (Pseudomorph)
Browse mineral (pseudomorph) specimens identified by the Rock Identifier community.
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Botryoidal Prehnite
Prehnite (Ca2Al(AlSi3O10)(OH)2)
mineral
Gneiss
Gneiss (a rock type, not a specific mineral with a formula)
Metamorphic Rock
Sandstone (likely Arkosic or Lithic)
Clastic Sedimentary Rock (SiO2 with accessory minerals)
sedimentary
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
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
Small pale mineral fragment
Unidentified; possibly quartz, calcite, or feldspar
mineral
Epidote
Epidote (Ca2(Al2,Fe3+)AlSi3O12(OH))
mineral
Small weathered fossil or mineral fragment
Indeterminate; possibly fossilized shell, bone, or a pale carbonate mineral
fossil
Limonite Ironstone
Goethite-Limonite concretion / Iron oxide
sedimentary
Turquoise and Hematite
Turquoise (CuAl6(PO4)4(OH)8·4H2O) and Hematite (Fe2O3)
mineral
Serpentine (likely serpentinite)
Serpentine-group minerals, chiefly antigorite, lizardite, and/or chrysotile; commonly with magnetite and minor brucite
metamorphic
Devil's Toenail (Fossil Oyster)
Gryphaea arcuata (Calcium Carbonate, CaCO3)
sedimentary
Banded Sandstone (Beach Pebble)
Quartz Arenite Sandstone
sedimentary
Schist
Schist (various mineral compositions)
Metamorphic
Serpentinite
Serpentine-group minerals, chiefly antigorite, lizardite, and chrysotile; approximate formula Mg3Si2O5(OH)4
metamorphic
Pebble with vesicles, likely basalt
Vesicular basalt; chiefly plagioclase, pyroxene, and iron-magnesium minerals
igneous
Limonite with Pyrite
Hydrated Iron Oxide Hydroxide, FeO(OH)·nH2O
mineral
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
Milky quartz (rough quartz crystal)
Quartz, silicon dioxide (SiO₂)
mineral
K-Feldspar (Potassium Feldspar)
Potassium Feldspar (KAlSi3O8)
mineral
Mica / Muscovite or Biotite
Phyllosilicate mineral group (e.g., KAl2(AlSi3O10)(OH)2)
mineral
Chalcopyrite (Peacock Ore)
Chalcopyrite (CuFeS2)
mineral
Botryoidal Chalcedony / Quartz
Silicon Dioxide (SiO2)
mineral
Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Mica (Muscovite or Biotite)
Sheet silicate mineral group (e.g., KAl2(AlSi3O10)(F,OH)2)
mineral
Feldspar
Aluminosilicate (KAlSi3O8 - NaAlSi3O8 - CaAl2Si2O8)
mineral
Epidote
Epidote (Ca2(Al,Fe)3(SiO4)3(OH))
mineral
Quartz with Sulfide Inclusions
Silicon Dioxide (SiO2) with metallic mineral inclusions
mineral
Granite
Granite (felsic intrusive igneous rock)
igneous
Unidentified metallic mineral or meteorite fragment
Indeterminate; possible native metal-bearing sulfide or iron meteorite fragment
mineral
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
Quartz (Druzy)
Silicon Dioxide (SiO2)
mineral
Ruby (Raw Corundum)
Corundum (Al2O3) with Chromium traces
mineral