Amethyst
Amethyst (Silicon Dioxide - SiO2 with iron impurities)
Category
Browse organic gemstone (sedimentary classification) specimens identified by the Rock Identifier community.
Amethyst
Amethyst (Silicon Dioxide - SiO2 with iron impurities)
Amethyst
Crystalline Quartz (SiO2 with iron impurities)
Quartz (possibly Citrine or Smoky Quartz variety)
Silicon Dioxide (SiO2)
Clear Quartz (Rock Crystal)
Silicon Dioxide (SiO2)
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2)
Aquamarine
Beryl (Be3Al2Si6O18 with Fe2+ impurities)
Banded Calcite (Tumbled)
Calcium Carbonate (CaCO3)
Agate Jasper
Cryptocrystalline Quartz (SiO2) with impurities
Quartz (Milky/Common)
Silicon Dioxide (SiO2)
Moonstone
Orthoclase (KAlSi3O8) with inclusions of Albite (NaAlSi3O8)
Amazonite
Amazonite (KAlSi3O8, a variety of Microcline)
Milky Quartz
Silicon Dioxide (SiO2)
Amethyst Quartz
Silicon Dioxide (SiO2 with iron impurities)
Shale
Fissile mudstone (Shale)
Fluorite in Matrix
Fluorite (CaF2) within a host rock matrix
Emerald
Beryl (Be3Al2(SiO3)6) with Chromium/Vanadium impurities
Silty Shale
Silty Shale (Fissile Sedimentary Rock)
Shale (Ferruginous)
Laminated Mudrock (Siliciclastic Sedimentary Rock)
Sandstone
Clastic sedimentary rock (primarily SiO2)
Shale (with Iron Oxide staining)
Fissile Mudstone (primarily Quartz and Clay minerals)
Pearl
Calcium Carbonate (Aragonite and Calcite), CaCO3
Green Quartzite
Meta-quartzite with Fuchsite inclusions (K(Al,Cr)2(AlSi3O10)(OH)2 + SiO2)
Sunstone (Oregon Sunstone)
Labradorite (Feldspar variety) - (Ca, Na)(Al, Si)4O8
Sunstone
Plagioclase Feldspar (Na,Ca)(Al,Si)4O8
Red Jasper (River pebble)
Jasper (Silicon Dioxide, SiO2 plus iron oxide impurities)
Rough Diamond
Diamond (pure Carbon, C)
Amethyst (Tumbled/Polished)
Silicon Dioxide (SiO2) with iron impurities
Amethyst
Silicon Dioxide (SiO2) with iron impurities
Tiger's Eye
Tiger's Eye (Pseudomorph of Quartz after Crocidolite), SiO2
Smoky Quartz
Smoky Quartz (Silicon Dioxide, SiO2)
Smoky Quartz
Silicon Dioxide (SiO2)
Carnelian (Red Chalcedony)
Silicon Dioxide (SiO2)
Carnelian Agate (with Quartz/Chalcedony)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
Herkimer Diamond
Quartz (Silicon Dioxide) - SiO2
Ruby (Pink to Red Corundum)
Al2O3 (Corundum with Chromium impurities)
Emerald
Beryl (Be3Al2Si6O18) with trace amounts of Chromium and/or Vanadium
Peridot (Olivine)
(Mg,Fe)2SiO4 (Magnesium Iron Silicate)
Turquoise
Hydrated phosphate of copper and aluminium (CuAl6(PO4)4(OH)8·4H2O)
Sedimentary Breccia
Breccia (Clastic Sedimentary Rock)
Gneiss
Gneiss (a type of metamorphic rock)
Quartz in Host Rock
Silicon Dioxide (SiO2) in Rhyolite or Granite matrix
Amethyst
Amethyst (Silicon Dioxide - SiO2 with ferric iron impurities)