Biotite Mica
Biotite (K(Mg,Fe)3AlSi3O10(F,OH)2)
Category
Browse mineral (gemstone) specimens identified by the Rock Identifier community.
Biotite Mica
Biotite (K(Mg,Fe)3AlSi3O10(F,OH)2)
Chert (often called Flint when dark)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Quartz
Quartz (SiO₂ - Silicon Dioxide)
Chert (Jasper/Flint variety)
Silicon Dioxide (SiO2)
Green Aventurine (likely)
Silicon dioxide (SiO2) with fuchsitemica inclusions
Sapphire (likely blue synthetic sapphire or blue glass in a ring)
Corundum (Al₂O₃), specifically the blue variety due to trace amounts of iron and titanium impurities. If synthetic, it would still be Al₂O₃.
Lapis Lazuli
Lapis lazuli (a metamorphic rock primarily composed of Lazurite, (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2)
Amber Inlay Jewelry
Fossilized Resin (C10H16O)
Jasper
Silicon dioxide (SiO2) with impurities
Red Jasper
Jasper (Silicon Dioxide with Iron Oxide inclusions, SiO2)
Unakite
Epidotized Granite
Yellow Quartzite Pebble
Quartzite (SiO2 with Iron Oxide staining)
Green Quartzite
Quartzite (SiO2 with chromium-rich muscovite/fuchsite inclusions)
Blue Lace Agate
Silicon Dioxide (SiO2) - Chalcedony / Quartz
Red Jasper
Jasper (Silicon Dioxide with Iron Oxide inclusions, SiO2)
Sodalite
Sodalite: Na8(Al6Si6O24)Cl2
Jasper
Silicon dioxide (SiO2) with impurities
Pink Opal
Hydrated Amorphous Silica (SiO2·nH2O)
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2 with inclusions of Iron Oxide)
Unakite
Unakite (Epidotized Granite)
Calcite
Calcite (CaCO₃)
Jasper and Chert Conglomerate
Ferruginous Microcrystalline Quartz (SiO2)
Jasper
Jasper (Silicon Dioxide) - SiO2
Pearl (Cultured or Natural)
Aragonite (CaCO3) with Conchiolin
Red Jasper
Silicon Dioxide with Iron Oxide inclusions (SiO2 + Fe2O3)
Red Jasper
Silicon Dioxide (SiO2)
Red Chert (Jasper)
Silicon Dioxide (SiO2) with iron oxide inclusions
Carnelian
Carnelian (a variety of Chalcedony, SiO ₂)
Garnet (likely Almandine or a blend)
Garnet group: X3Y2(SiO4)3, where X can be Ca, Mg, Fe2+, Mn2+ and Y can be Al, Fe3+, Cr3+. Given the dark, somewhat reddish-brown appearance in the image, it's likely Almandine (Fe3Al2(SiO4)3) or a mix with other iron-rich garnets.
Amber
Succinite (specifically for Baltic amber; fossilized tree resin)
Bloodstone
Heliotrope (a variety of Chalcedony, SiO₂ with inclusions)
Zircon
Zircon (ZrSiO4)
Quartz (likely Milky Quartz or Chalcedony)
Quartz (SiO2 - Silicon Dioxide)
Chert (specifically Flint)
Microcrystalline or cryptocrystalline Quartz (SiO2)
Amber
Succinite (specifically for Baltic amber); Approximate formula: C10H16O
Petoskey Stone (Fossilized Coral)
Hexagonaria percarinata (CaCO3)
Jasper (Mookaite style)
Silicon Dioxide (SiO2) with iron and manganese inclusions
Ocean Jasper (Orbicular Jasper)
Spherulitic Chalcedony (SiO2)
Yellow Aventurine
Quartzite with Muscovite/Sericite inclusions (SiO2 + KAl2(AlSi3O10)(OH)2)
Dalmatian Stone (Dalmatian Jasper)
Dalmatian Stone (A variety of Perthite / Aplite)
Unakite
Epidotized Granite
Apache Tear
Hydrated Obsidian (Natural Volcanic Glass)