Quartz
Silicon Dioxide (SiO2)
Category
Browse organic gemstone (not a rock) specimens identified by the Rock Identifier community.
Quartz
Silicon Dioxide (SiO2)
Quartz
Silicon Dioxide (SiO2)
Labradorite (tumbled)
Labradorite (a plagioclase feldspar mineral between anorthite and albite; chemical formula: (Ca,Na)(Si,Al)4O8)
Quartz (likely Milky Quartz or Chalcedony)
Quartz (SiO2 - Silicon Dioxide)
Peridot (Olivine)
Olivine, (Mg,Fe)2SiO4
Fluorite in Matrix
Fluorite (CaF2) within a host rock matrix
Lapis Lazuli
Lapis Lazuli (a rock composed primarily of Lazurite (Na,Ca)₈[(S,Cl,SO₄,OH)₂|(Al₆Si₆O₂₄)], with varying amounts of Calcite, Pyrite, and Sodalite.)
Epidote
Epidote Group (e.g., Clinozoisite, Epidote, Piemontite), Epidote formula: Ca2(Al,Fe)3(SiO4)3(OH)
Baltic Amber (Butterscotch or Egg Yolk Variety)
Succinite (C10H16O)
Rough Garnet in Matrix
Almandine Garnet (Fe3Al2Si3O12)
Tiger's Eye
Tiger's Eye (a variety of Quartz, SiO₂)
Quartz (likely a form of massive or vein quartz)
Quartz (SiO₂)
Sapphire
Corundum (Al₂O₃) with trace elements causing color variations.
Prehnite
Prehnite, Ca2Al2Si3O10(OH)2
Garnet (Red Garnet)
Garnet Group. The red varieties seen in jewelry are typically Almandine (Fe3Al2(SiO4)3), Pyrope (Mg3Al2(SiO4)3), or a mix of the two (pyrope-almandine series).
Quartz (likely macrocrystalline variety)
Quartz (SiO₂)
Amethyst
Quartz variety; chemical formula: SiO₂ (silicon dioxide) with Fe³⁺ impurities
Citrine
SiO2 (Silicon Dioxide)
Demantoid Garnet on Matrix
Demantoid (variety of Andradite Garnet) - Ca3(Fe3+)2(SiO4)3
Anthracite Coal
Anthracite (Carbon-based organic sedimentary rock exposed to metamorphic heat/pressure; Chemical composition is approximately 86%–98% Carbon)
Larimar
Pectolite (a blue variety of Pectolite)
Red Jasper
Jasper (a variety of Chalcedony, SiO₂ with iron oxide inclusions)
Amazonite
KAlSi3O8 (Potassium Feldspar, variety of Microcline)
Serpentinite
Serpentinite
Quartz (in a rock matrix)
Quartz (SiO2)
Rutilated Quartz
Quartz (SiO2) with Rutile (TiO2) inclusions
Amazonite
KAlSi3O8 (Potassium Feldspar, variety of Microcline)
Blue Quartzite
Quartzite (specifically a variety enriched with blue-coloring minerals)
Agate (various color varieties)
SiO₂ (Silicon Dioxide)
Ruby
Corundum (mineral species), variety: Ruby (Al2O3 with Cr3+ as the chromophore)
Green glass sphere/marble
Soda-lime glass (primarily SiO2, Na2O, CaO)
Carnelian
Chalcedony (cryptocrystalline quartz), SiO2
Quartz (chalcedony variety) or Limestone with Quartz Veins
SiO2 (for Quartz/Chalcedony); CaCO3 (for Limestone)
Quartz
Silicon dioxide (SiO2)
Biotite Mica
Biotite (K(Mg,Fe)3AlSi3O10(F,OH)2)
Quartz
Quartz (SiO2 - Silicon Dioxide)
Quartz (likely tumbled or naturally water-worn)
Quartz (SiO₂ - Silicon Dioxide)
White Quartz
Quartz (SiO2)
Garnet (likely Almandine or Pyrope)
Garnet Group (e.g., Almandine: Fe3Al2(SiO4)3; Pyrope: Mg3Al2(SiO4)3)
Chrysoprase
Chalcedony (cryptocrystalline quartz) with nickel inclusions; SiO2
Corundum
Corundum (Al2O3)
Quartz (variety of colors)
SiO2 (Silicon Dioxide)