Organic Gemstone (Not A Rock Or Mineral)

Chert (White Chert/Flint)

Chert (Microcrystalline or Cryptocrystalline Quartz, SiO2)

Peridot (Olivine)

Magnesium Iron Silicate (Mg, Fe)2SiO4

Gneiss

High-grade regional metamorphic rock (Foliated)

Moss Agate

Chalcedony (SiO2) with inclusions of manganese or iron oxides

Veined Limestone (Micrite) with Quartz/Calcite Veins

Calcium Carbonate (CaCO3) with Silicate or Carbonate inclusions

Petrified Wood

Silicified Wood (SiO2)

Sandstone (with Iron Staining)

Clastic sedimentary rock (SiO2 with Fe2O3 oxides)

Chert (Flint variety)

Chert (SiO2)

Chert (varieties include Flint and Jasper)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Peacock Ore

Bornite (Cu5FeS4) or Chalcopyrite (CuFeS2) with iridescent tarnish

Sandstone

Clastic sedimentary rock (primarily SiO2)

Garnet (likely Almandine or Pyrope)

Garnet Group (e.g., Almandine: Fe3Al2(SiO4)3; Pyrope: Mg3Al2(SiO4)3)

Petrified Wood (Calamites Fossil)

Calamites sp. (Silicified/Permineralized Plant Fossil)

Petrified Wood

Silicified Wood (SiO2)

Petrified Wood

Silicified Wood (primarily Quartz/Chalcedony, SiO2)

Chert / Flint

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Slate with Quartz Vein

Foliated Metamorphic Rock (Mainly Quartz, Muscovite, Chlorite)

Quartz-veined Mudstone or Argillite

SiO2 (Quartz) in Siltstone/Mudstone matrix

Zebra Jasper

Tetragonal Silicon Dioxide (Quartz) with impurities

Lapis Lazuli

Lazurite-rich metamorphic rock (complex silicate)

Asphalt / Bituminous Aggregate

Bituminous mixture (Hydrocarbon-based sediment)

Quartz Mineral

Silicon Dioxide (SiO2)

Chert (Flint variety)

Microcrystalline context of Quartz (SiO2)

Peridot

Olivine (Magnesium Iron Silicate - (Mg, Fe)2SiO4)

Picture Jasper

Silicon Dioxide (SiO2) with iron oxide and organic impurities

Gneiss

Foliated Metamorphic Rock (Gneiss)

Malachite with Chrysocolla

Copper carbonate hydroxide (Cu2CO3(OH)2) and Hydrated copper silicate (Cu,Al)2H2Si2O5(OH)4·nH2O

Prehnite

Prehnite (Ca2Al(AlSi3O10)(OH)2)

Prehnite

Prehnite (Ca2Al(AlSi3O10)(OH)2)

Ironstone Concretion (Limonite/Goethite)

Iron oxide concretion (contains FeO(OH)·nH2O)

Citrine Quartz

Silicon Dioxide (SiO2)

Peridot

Olivine (Mg, Fe)2SiO4

Citrine

Crystalline Quartz (SiO2) with iron impurities

Chert (Flint)

Silicon Dioxide (SiO2)

Chert (Jasper)

Microcrystalline Silica (SiO2)

Spiny Oyster Shell

Spondylus (Calcium Carbonate, CaCO3)

Granite

Plutonic felsic rock (Quartz, Feldspar, Mica)

Rutilated Quartz

Quartz (SiO2) with Rutile (TiO2) inclusions

Banded Slate or Siltstone with Quartz/Calcite Veins

Protolith-derived Siltstone or Slate (varies based on degree of metamorphism)

Aquamarine

Beryl (Be3Al2Si6O18)

Chert Pebble (Jasper/Quartz variety)

Microcrystalline Quartz (SiO2)

Granite with Epidote

Granite, containing quartz, feldspar, and epidote