Obsidian
Extrusive igneous volcanic glass (rich in SiO2)
Category
Browse mineral precipitate (anthropogenic context) specimens identified by the Rock Identifier community.
Obsidian
Extrusive igneous volcanic glass (rich in SiO2)
Quartz
Quartz (Silicon Dioxide, SiO2)
Quartz
Silicon Dioxide (SiO2)
Quartz (Milky/Crystalline variety)
Silicon Dioxide (SiO2)
Ruby and Diamond Heart Pendant
Corundum (Al2O3) and Diamond (C)
Quartz Pebble
Silicon Dioxide (SiO2)
Quartz (Milky to Clear)
Silicon Dioxide (SiO2)
Quartz (possibly Citrine or Smoky Quartz variety)
Silicon Dioxide (SiO2)
Schist
Mica Schist
Himalayan Salt
Halite (mineral name), chemical formula NaCl (sodium chloride). Generally, 'Himalayan Salt' is a trade name for evaporite minerals from specific regions.
Schist
Mica Schist
Sandstone
Arenite (primarily Quartz, SiO2)
Smoky Quartz and Feldspar Pegmatite
Granitic Pegmatite (chiefly SiO2 and KAlSi3O8)
Ironstone with Pyrite
Ferruginous Sandstone (Fe2O3) with minor Sulfide minerals (FeS2)
Aragonite Star Cluster (or Aragonite Sputnik)
Aragonite (Orthorhombic Calcium Carbonate, CaCO3)
Marble
Recrystallized Calcite (CaCO3)
Amethyst and Peridot
Amethyst (SiO2 with iron impurities) and Peridot ((Mg, Fe)2SiO4)
Septarian Nodule
Septarian Concretion (Calcium Carbonate/Aragonite/Calcite)
Blue Sapphire
Corundum (Al2O3)
Yellow Calcite
Calcium Carbonate (CaCO3)
Quartz Geode
Silicon Dioxide (SiO2) within a geode
Quartz Geode
Silicon Dioxide (SiO2)
Agate
Silicon dioxide (SiO2)
Peridot
Olivine (Magnesium Iron Silicate), (Mg, Fe)2SiO4
Satin Spar (Selenite)
Gypsum (Calcium Sulfate Dihydrate) - CaSO4·2H2O
Pyrite (Fool's Gold)
Iron Disulfide (FeS2)
Gneiss
Gneiss
Basalt
Mafic Igneous Rock
Green Calcite
Calcium Carbonate (CaCO3)
White Marble
Recrystallized Calcite (CaCO3)
Blue Spinel on Marble with Phlogopite
MgAl2O4 (Spinel) in CaCO3 (Calcite/Marble) matrix
Banded Slate or Siltstone with Quartz/Calcite Veins
Protolith-derived Siltstone or Slate (varies based on degree of metamorphism)
Amygdaloidal Basalt with Quartz/Zeolite Infill
Amygdaloidal Basalt (extrusive volcanic rock with SiO2 or CaAl2Si3O10·3H2O infill)
Quartz
Silicon Dioxide (SiO2)
Granite
Granite (Felsic intrusive igneous rock)
Greenschist (Greenstone)
Chlorite Schist / Greenschist Facies Rock
Amethyst (Quartz)
Silicon Dioxide (SiO2)
Green Quartz (Prasiolite/Adventurine)
Silicon Dioxide (SiO2) with inclusions
Alexandrite in Matrix
Chrysoberyl (BeAl2O4 with Chromium impurities)
Citrine Quartz Crystal Cluster
Silicon Dioxide (SiO2) with iron impurities
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2 with Iron Oxide)
Hypersthene
Hypersthene ((Mg,Fe)SiO3)