Vesicular basalt (likely weathered volcanic rock)
Basalt, commonly composed of plagioclase, pyroxene, and olivine
Category
Browse igneous or sedimentary (anthropogenic modification) specimens identified by the Rock Identifier community.
Vesicular basalt (likely weathered volcanic rock)
Basalt, commonly composed of plagioclase, pyroxene, and olivine
Basalt
Fine-grained mafic volcanic rock, chiefly plagioclase feldspar, pyroxene, and commonly olivine
Slag
Metallurgical Slag
Milky quartz (quartz crystal)
Quartz, silicon dioxide (SiO₂)
Red Jasper
Silicon Dioxide (SiO2) - variety of Chalcedony
Quartz (likely Rose Quartz or Milky Quartz based on color)
Quartz (SiO2 - Silicon Dioxide)
Dark metamorphic rock, likely biotite schist or gneiss
Quartz–feldspar–biotite metamorphic rock; exact identification requires a fresh surface and testing
Specular Hematite
Hematite (Fe2O3)
Gneiss
Gneiss
Quartz
Silicon Dioxide (SiO2)
Granitic Gneiss Pebble
Gneiss (felsic metamorphic rock)
Rough Diamond (or Quartz Crystal)
Carbon (C) [if Diamond] / Silicon Dioxide (SiO2) [if Quartz]
Gneiss
Gneiss (High-grade Regional Metamorphic Rock)
Quartz Crystal (specifically a small Clear Quartz point)
Silicon Dioxide (SiO2)
Blue Calcite
Calcium Carbonate (CaCO3)
Green Fluorite
Fluorite (Calcium Fluoride, CaF2)
Greenstone / Graywacke
Metagraywacke (Chlorite-grade schistose rock)
Yellow Agate
Chalcedony (cryptocrystalline Quartz), SiO2
Gneiss
Gneiss
Chalcedony (Agate)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
Carnelian
Carnelian Agate (Silica: SiO2)
Pyrite (Iron Pyrite)
Iron Sulfide (FeS2)
Granite Gneiss
High-grade regional metamorphic rock (Quartz-Feldspar Gneiss)
Agate Geode
Cryptocrystalline Quartz (SiO2)
Gneiss
Gneiss (High-grade Regional Metamorphic Rock)
Milky Quartz
Silicon Dioxide (SiO2)
Pyrite
Iron Sulfide (FeS2)
Milky Quartz Pebble
Quartz (Silicon Dioxide, SiO2)
Quartz (Smoky/Milky variety)
Silicon Dioxide (SiO2)
Fluorite
Calcium Fluoride (CaF2)
Gneiss (Granitic Gneiss)
Gneiss (from German Gneis, related to 'spark')
Pyrite
Iron Disulfide (FeS2)
Hematite
Hematite (Fe2O3)
Fluorite (Rainbow Fluorite Point)
Calcium Fluoride (CaF2)
Hematite
Iron(III) oxide (Fe2O3)
Pyrite (Fool's Gold)
Iron Sulfide (FeS2)
Mica Schist (with Golden/Biotite inclusions)
K(Mg,Fe)3AlSi3O10(F,OH)2 (Biotite), KAl2(AlSi3O10)(F,OH)2 (Muscovite)
Dark river pebble (likely basalt or andesite)
Fine-grained mafic/intermediate volcanic rock; commonly basalt (plagioclase ± pyroxene/olivine)
Labradorite (tumbled)
Labradorite (a plagioclase feldspar mineral between anorthite and albite; chemical formula: (Ca,Na)(Si,Al)4O8)
Black Sand (Magnetite/Heavy Mineral Concentrate)
Magnetite-rich Placers (Fe3O4)
Arkosic Sandstone
Arkose
Quartz
SiO₂ (Silicon Dioxide)