Prehnite
Prehnite (Ca2Al(AlSi3O10)(OH)2)
Category
Browse mineral like byproduct (technogenic) specimens identified by the Rock Identifier community.
Prehnite
Prehnite (Ca2Al(AlSi3O10)(OH)2)
Dendritic Quartz Pebble
Silicon Dioxide (SiO2) with Manganese/Iron oxide inclusions
Obsidian
Volcanic Glass (Amorphous Silica)
Quartz (Clear Quartz/Rock Crystal)
Silicon Dioxide (SiO2)
Yellow Calcite
Calcium Carbonate (CaCO3)
Gneiss (Metamorphic Cobble)
Gneiss
Sulfur
Native Sulfur (S8)
Obsidian
Volcanic Glass (SiO2 + minor impurities)
Sandstone (Ferruginous)
Arenite with Iron Oxides
Gneiss
Gneiss
Sodalite
Sodalite (Na8Al6Si6O24Cl2)
Ruby in Kyanite
Corundum in Disthene (Al2SiO5 + Al2O3)
Quartz Geode
Silicon Dioxide (SiO2)
Magnetite
Magnetite (Fe3O4)
Fluorite
Calcium Fluoride (CaF2)
Limonite (Iron Ore)
Limonite (FeO(OH)·nH2O)
Obsidian
Volcanic Glass (predominantly SiO2)
Sandstone
Arenite
Prehnite
Prehnite - Ca2Al(AlSi3O10)(OH)2
Rutilated Quartz (with Garnet pendant)
Silicon Dioxide (SiO2) with Titanium Dioxide (TiO2) inclusions
Turquoise
Hydrated copper and aluminum phosphate (CuAl6(PO4)4(OH)8·4H2O)
Dendritic Agate
Silicon Dioxide with Manganese or Iron Oxide inclusions (SiO2 + Mn/Fe)
River Stone (likely Mudstone or Siltstone)
Lutite (Clastic sedimentary rock composed of clay and silt-sized particles)
Clear Quartz
Quartz (Silicon Dioxide, SiO2)
Smoky Quartz
Smoky Quartz (Silicon Dioxide - SiO2)
Basalt with Secondary Mineralization (Likely Zeolites or Calcite)
Aphanitic mafic volcanic rock with secondary mineral inclusions (e.g., CaAl2Si3O10·3H2O for Scolecite)
Mica Schist
Mica Schist (Schistose metamorphic rock rich in Muscovite/Biotite)
Black Obsidian
Volcanic Glass (SiO2 + impurities like Fe3O4)
Petrified Wood
Silicified Wood (SiO2 - Quartz/Chalcendony replacing organic matter)
White Calcite
Calcium Carbonate (CaCO3)
Limonite Concretion
Limonite (Hydrated Iron Oxide) FeO(OH)·nH2O
Petrified Wood
Silicified wood (primarily Silicon Dioxide, SiO2)
Rugose Coral (Horn Coral)
Order Rugosa (extinct fossilized coral)
Sandstone (with Concretion)
Arenite / Quartzose Sandstone
Sandstone (River Rock)
Arenite (composed primarily of SiO2)
Apatite
Apatite Group (e.g., Fluorapatite Ca5(PO4)3F, Chlorapatite Ca5(PO4)3Cl, Hydroxylapatite Ca5(PO4)3(OH))
Iolite (Cordierite)
Magnesium Iron Aluminum Silicate (Mg,Fe)2Al4Si5O18
Milky Quartz
Silicon Dioxide (SiO2)
Sandstone
Arenite (primarily Quartz, SiO2)
Mica Schist
Mica Schist (Composition typically contains Muscovite: KAl2(AlSi3O10)(OH)2 or Biotite: K(Mg,Fe)3AlSi3O10(OH)2 along with Quartz and Feldspar)
Sunstone
Heliolite (Oligoclase or Orthoclase Feldspar), (Ca,Na)(Al,Si)4O8
Jasper with Quartz Veining
Silicon Dioxide (SiO2) with impurities