Prehnite
Ca2Al(AlSi3O10)(OH)2
mineral
Category
Mineral, Organic Gemstone
Browse mineral, organic gemstone specimens identified by the Rock Identifier community.
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Emerald
Beryl (Be3Al2(SiO3)6)
gemstone
Quartz
Silicon Dioxide (SiO2)
mineral
Smoky Quartz in Matrix
Silicon Dioxide (SiO2)
mineral
Emerald in Matrix
Beryl (Be3Al2Si6O18 with Chromium/Vanadium traces)
gemstone
Prehnite
Prehnite (Ca2Al(AlSi3O10)(OH)2)
mineral
Prehnite
Prehnite (Ca2Al(AlSi3O10)(OH)2)
mineral
Sunstone
Oligoclase (Plagioclase Feldspar), (Na,Ca)(Si,Al)4O8
mineral
Turquoise
Turquoise, CuAl6(PO4)4(OH)8·4H2O
mineral
Amethyst
Silicon dioxide (SiO2) with iron impurities
mineral
Prehnite
Prehnite (Ca2Al(AlSi3O10)(OH)2)
mineral
Malachite with Chrysocolla
Copper carbonate hydroxide (Cu2CO3(OH)2) and Hydrated copper silicate (Cu,Al)2H2Si2O5(OH)4·nH2O
mineral
Prehnite
Prehnite (Ca2Al(AlSi3O10)(OH)2)
mineral
Petrified Wood
Silicified wood (Quartz/Chalcedony replacement of cellulose)
sedimentary
Chert with Iron Oxide Staining
Microcrystalline Quartz (SiO2) with Limonite/Goethite staining
sedimentary
Jasper
Silicon Dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Jasper
Microcrystalline Quartz (SiO2)
sedimentary
Petrified Wood
Silicified Wood (SiO2)
mineral
Pearl (Cultured or Natural)
Aragonite (CaCO3) with Conchiolin
Organic Mineraloid
Banded Chert
Microcrystalline Quartz (SiO2)
sedimentary
Druzy Chalcedony/Quartz on Fluorite core
Silicon Dioxide (SiO2) on Calcium Fluoride (CaF2)
mineral
Petrified Wood
Silicified wood (primarily SiO2 - Silicon Dioxide/Quartz)
metamorphic
Quartz (Milky/Rose variety)
Silicon Dioxide (SiO2)
mineral
Chrysocolla
Cu2-xAlx(H2-xSi2O5)(OH)4·nH2O
mineral
Vivianite
Vivianite, Fe2+3(PO4)2·8H2O
mineral
Petrified Wood
Silicified Wood (SiO2)
mineral
Pyrite in Shale
Iron Disulfide (FeS2) in Sedimentary Shale
mineral
Petrified Wood
Silicified Wood (SiO2)
mineral
Moss Agate
Silicon Dioxide with inclusions (SiO2 + impurities)
mineral
Amber (Rough)
Amber (Fossilized Tree Resin, succinite)
mineral
Pyrite
Iron Sulfide (FeS2)
mineral
Petrified Wood
Silicified Wood (SiO2)
mineral
Petrified Wood
Silicified Wood (primarily Quartz/SiO2)
fossil
Chert (Jasper/Flint variety)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Quartz Crystal Cluster
Silicon Dioxide (SiO2)
mineral
Fossil Coral
Scleractinia (Fossilized Coral) / Calcium Carbonate (CaCO3) or Silica (SiO2)
fossil
Moss Agate
Silicon Dioxide (SiO2) with inclusions
mineral
Moss Agate
Chalcedony (Silicon Dioxide) with dendritic inclusions (SiO2)
Mineral
Petrified Wood
Silicified Wood (primarily SiO2)
fossil
Amethyst
Amethyst (Silicon Dioxide, SiO2)
mineral
Concrete or asphalt-like aggregate surface with a dark fragment
Uncertain; likely artificial concrete containing mixed lithic aggregate, not a natural rock
sedimentary
Turquoise
CuAl6(PO4)4(OH)8·4H2O
mineral