Carnelian
Carnelian Chalcedony (SiO2 with iron oxide impurities)
Category
Browse organic gemstone (not a rock or mineral in the traditional sense, but bio mineralized material) specimens identified by the Rock Identifier community.
Carnelian
Carnelian Chalcedony (SiO2 with iron oxide impurities)
Amethyst
Amethyst (Silicon Dioxide, SiO2 + Fe)
Chert (varietal Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Granite
Phaneritic Felsic Igneous Rock (primarily Quartz, Alkali Feldspar, and Plagioclase)
Quartzite with Quartz Vein
Metamorphosed Quartz-rich Arenite (SiO2)
Clear Quartz Point
Silicon Dioxide (SiO2)
Sodalite
Sodalite (Na8Al6Si6O24Cl2)
Sodalite
Sodalite (Na8(Al6Si6O24)Cl2)
Tektite (likely Australite)
Tektite (no specific chemical formula as it's a natural glass of variable composition, mostly SiO2, Al2O3, FeO, MgO, CaO, K2O, Na2O, TiO2)
Quartz / Chert
Silicon Dioxide (SiO2)
Banded Agate
Cryptocrystalline Quartz (SiO2)
Blue Sapphire
Corundum (Al2O3)
Smoky Quartz
Silicon Dioxide (SiO2)
Amethyst
SiO2 (Silicon Dioxide with iron impurities)
Clear Quartz
Silicon Dioxide (SiO2)
Quartz
Silicon Dioxide (SiO2)
Diamond (Green tinted)
Carbon (C) with trace impurities or lattice defects
Granite
Granite (Phaneritic intrusive igneous rock)
Quartz with Iron Stains
Quartz (SiO2) with iron oxide/hydroxide staining
Greenschist
Greenschist facies rock (containing chlorite, actinolite, albite, and epidote)
Quartz
Quartz (SiO₂)
Smoky Quartz
Silicon Dioxide (SiO2)
Quartz (Quartzite fragment)
Silicon Dioxide (SiO2)
Carnelian (Agate)
SiO2 (Silicon Dioxide with Iron Oxide impurities)
Quartz Pebble (Milky Quartz)
Silicon Dioxide (SiO2)
Rough Aquamarine
Beryl (Be₃Al₂Si₆O‑₁•H₂O)
Sodalite
Sodalite (Na8Al6Si6O24Cl2)
Tufa
Calcareous Tufa (CaCO3)
Smoky Quartz
Silicon Dioxide (SiO2)
Epidote in Basalt
Epidotized Basalt (Ca2(Al2,Fe)(SiO4)(Si2O7)O(OH) in Mafic Igneous Host)
Diorite (Salt and Pepper Rock)
Phaneritic plutonic igneous rock (sodium-rich plagioclase feldspar and hornblende)
Granite
Granite (a plutonic rock)
Laterite
Laterite (Ferricrete)
Garnet (Almandine)
Almandine (Fe3Al2(SiO4)3)
Milky Quartz with Matrix
Quartz (Silicon Dioxide, SiO2)
Tiger's Eye
SiO2 (Silicon Dioxide with inclusions of Goethite/Limonite)
Quartz (Iron-stained)
Silicon Dioxide (SiO2) with Hematite/Limonite impurities
Amber
Succinite (specifically for Baltic Amber), Formula: C10H16O
Pink Tourmaline (Rubellite)
Elbaite (Tourmaline group) - Na(Li,Al)3Al6(BO3)3Si6O18(OH)4
Red Jasper or Chert
Jasper (SiO2, a variety of chalcedony with iron oxide impurities), Chert (SiO2)
Rose Quartz
Silicon Dioxide (SiO2) with trace amounts of titanium, iron, or manganese
Yellow Agate
Chalcedony (cryptocrystalline silica), SiO2