Chert / Flint
Cryptocrystalline Quartz (Silicon Dioxide, SiO2)
Category
Browse organic gemstone (not a rock or mineral in the traditional sense, but bio mineralized material) specimens identified by the Rock Identifier community.
Chert / Flint
Cryptocrystalline Quartz (Silicon Dioxide, SiO2)
Hag Stone
Calcareous sedimentary rock (often Chert, Flint, or Limestone)
Amethyst
Amethyst (Silica mineral, SiO2)
Amethyst
Silicon Dioxide (SiO2) with iron impurities
Petrified Wood
Silicified Wood (SiO2 - Silicon Dioxide)
Red Jasper
Silicon dioxide (SiO2) with iron oxide (Fe2O3) inclusions
Jasper with Chert
Silicon Dioxide (SiO2) - Microcrystalline Quartz
Jasper
Jasper (Silica-rich microcrystalline Quartz, SiO2 with Fe2O3 impurities)
Petrified Wood
Silicified wood (Quartz/Chalcedony replacement of organic matter)
Carnelian (Orange Chalcedony)
Silicon Dioxide (SiO2)
Petrified Wood
Silicified Wood (primarily SiO2)
Petrified Wood
Silicified Wood (SiO2)
Chert (Cherty Flint/Jasper variety)
Microcrystalline or cryptocrystalline Quartz (SiO2)
Shale
Fissile Clay-dominant Mudrock (SiO2, Al2O3, K2O, Na2O, CaO, MgO)
Nephrite Jade
Nephrite
Petrified Wood
Silicified Wood (primarily Quartz/Chalcedony, formula SiO2)
Grass (Organic Matter/Soil)
Poaceae (family of monocotyledonous flowering plants)
Petrified Wood
Silicified Wood (SiO2)
Chert Pebble with Quartz Veins
Microcrystalline Quartz (SiO2)
Almandine Garnet
Almandine, Fe3Al2(SiO4)3
Ferruginous Quartz
Silicon Dioxide (SiO2) with Hematite/Limonite impurities
Slate
Foliated Metamorphic Rock (composed primarily of silica and alumina with iron and magnesium)
Nephrite Jade
Nephrite
Petrified Wood
Silicified Wood (SiO2)
Petrified Wood
Silicified Wood (primarily Quartz/Chalcedony, SiO2)
Aquamarine
Beryl (Be3Al2Si6O18)
Chert (Yellow Jasper/Flint)
Silicon Dioxide (SiO2)
Quartz (Druzy or Crystalline variety)
Silicon Dioxide (SiO2)
Chert (Jasper variety)
Silicon Dioxide (SiO2)
Quartz (likely Rose Quartz or Milky Quartz based on color)
Quartz (SiO2 - Silicon Dioxide)
Graphite-veined Quartzite
Meta-sedimentary Quartzite with Carbonaceous/Graphitic Inclusions (SiO2 + C)
Ruby
Corundum (Aluminium Oxide with Chromium impurities, Al2O3:Cr)
Moss Agate
Moss Agate (a variety of Chalcedony, SiO ₂)
Amber
Succinite (specifically for Baltic Amber), Formula: C10H16O
Shale
Shale
Ironstone Concretion (Limonite/Hematite Nodules)
Ironstone (principally Limonite FeO(OH)·nH2O or Hematite Fe2O3 mixed with silica/clay)
Amber
Succinite (C10H16O)
Natural White Pearl
Calcium Carbonate (Aragonite/Calcite) with Conchiolin - CaCO3
Milky Quartz
Silicon Dioxide (SiO2)
Shungite
Non-crystalline carbon (allotrope of carbon)
Coral Fossil (Scleractinia)
Scleractinia (Order), primarily CaCO3 (Aragonite or Calcite)
Petrified Wood
Silicified Wood (SiO2)