Citrine
Silicon dioxide (SiO2)
mineral
Category
Mineral (Biogenic)
Browse mineral (biogenic) specimens identified by the Rock Identifier community.
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Sunstone
Plagioclase Feldspar (Na,Ca)(Al,Si)4O8
mineral
Amethyst
Quartz (Silicon Dioxide with Iron impurities), SiO2
mineral
Amazonite
KAlSi3O8 (Potassium aluminum silicate - blue-green variety of Microcline)
mineral
Quartz (Iron-Stained)
Crystalline Silicon Dioxide (SiO2)
mineral
Fire Opal (in Matrix)
Hydrated Silica (SiO2·nH2O)
mineral
Chert (Flint Pebbles)
Microcrystalline Quartz (SiO2)
sedimentary
Jasper
Silicon dioxide (Microcrystalline Quartz, SiO2)
sedimentary
Sunstone
Oligoclase (Plagioclase Feldspar), (Ca,Na)(Al,Si)4O8
mineral
Prehnite
Prehnite (Ca2Al(AlSi3O10)(OH)2)
mineral
Amazonite
Potassium Aluminum Silicate (KAlSi3O8)
mineral
Chalcedony (Agate Pebble)
Silicon Dioxide (SiO2)
mineral
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2)
metamorphic
Smoky Quartz with Feldspar
SiO2 (Quartz) with KAlSi3O8 (Potassium Feldspar)
mineral
Prehnite
Prehnite, Ca2Al2Si3O10(OH)2
mineral
Tiger's Eye
Fibrous Quartz (SiO2) with iron inclusions
mineral
Rough Quartz (Milky Quartz Pebbles)
Silicon Dioxide (SiO2)
mineral
Gossan (Iron Hat) with Quartz and Chlorite
Limonite/Goethite-rich Gossan (FeO(OH)·nH2O) with inclusions of Quartz and Chlorite
Mineral/Metamorphic Substrate
Lazulite
Lazulite (Mg,Fe2+)Al2(PO4)2(OH)2
mineral
Banded Calcite (often sold as 'Mexican Onyx' or 'Calcite Onyx')
Calcite (Calcium Carbonate, CaCO3)
sedimentary
Quartz with inclusions (likely Chlorite or Hornblende) and country rock
SiO2 (Quartz) with associated ferromagnesian minerals
Mineral/Igneous/Metamorphic association
Granite
Granite (composed mainly of Quartz, Feldspar, and Mica)
igneous
Shale
Shale
sedimentary
Gneiss (likely)
Gneiss
Metamorphic
Granite fragment
Granite (Felsic Plutonic Rock)
igneous
Fossilized Oyster Shell
Exogyra or Ostrea (Gryphaeidae/Ostreidae family)
fossil
Sandstone (Ferruginous)
Arenite (composed primarily of SiO2 with Fe2O3 cement)
sedimentary
Malachite
Copper carbonate hydroxide Cu2CO3(OH)2
mineral
Sandstone (Ferruginous)
Arenite (Fe-rich)
sedimentary
Red Sandstone
Clastic sedimentary rock (primarily SiO2 with Fe2O3)
sedimentary
Red Sandstone
Arenite (primarily Quartz with Hematite cement)
sedimentary
Black Marble
Recrystallized Calcite (CaCO3)
metamorphic
Sandstone with Iron Oxide Staining
Clastic sedimentary rock (primarily SiO2 with Fe2O3 staining)
sedimentary
Sandstone (Red Sandstone)
Clastic Sedimentary Rock (primarily SiO2 with Iron Oxide)
sedimentary
Red Sandstone
Arenite (with Iron Oxide)
sedimentary
Sandstone (with Iron Staining)
Clastic Sedimentary Rock (primarily SiO2 with Fe2O3 oxides)
sedimentary
Sandstone (Quartzose)
Arenite (primarily SiO2)
sedimentary
Red Sandstone
Arenite with iron oxide (Hematite) cement
sedimentary
Turquoise (Blue Howlite / Magnesite imitation)
CuAl6(PO4)4(OH)8·4H2O (for natural Turquoise); Ca2B5SiO9(OH)5 (for Howlite)
mineral
Amygdaloidal Basalt
Amygdaloidal Basalt (Mafic Extrusive)
igneous
Granite
Granite (felsic intrusive igneous rock)
igneous
Blue Apatite
Apatite (Calcium Phosphate) - Ca5(PO4)3(F,Cl,OH)
mineral