Sedimentary (Fossilized Organic Matter)

Fluorite

Calcium Fluoride (CaF2)

Gneiss

Gneiss

Chalcedony / Agate

Silicon Dioxide (SiO2)

Fluorite

Calcium Fluoride (CaF2)

Caribbean Calcite

Calcium Carbonate (CaCO3) with Aragonite (CaCO3)

Quartz / Milky Quartz

Silicon Dioxide (SiO2)

Turquoise

CuAl6(PO4)4(OH)8·4H2O

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Limonite (Iron Ore)

Limonite (FeO(OH)·nH2O)

Blue Chalcedony

Silicon Dioxide (SiO2)

Agate with Druzy Quartz

Silicon Dioxide (SiO2)

Hematite (Iron Ore)

Hematite (alpha-Fe2O3)

Clear Quartz

Silicon Dioxide (SiO2)

Yellow Calcite

Calcite (Calcium Carbonate, CaCO3)

Aragonite (Banded Calcite / 'Mexican Onyx')

Aragonite (Calcium Carbonate - CaCO3)

Limonite

Limonite (FeOO·nH2O)

Zoisite with Ruby (Anyolite)

Zoisite – Ca2Al3(SiO4)3(OH) with inclusions of Ruby (Al2O3:Cr)

Selenite (Satin Spar)

Gypsum (CaSO4·2H2O)

Orange Calcite

Calcium Carbonate (CaCO3)

Clear Quartz

Silicon Dioxide (SiO2)

Botryoidal Chalcedony

Silicon Dioxide (SiO2)

Rhodochrosite

Manganese carbonate (MnCO3)

Satin Spar Selenite

Calcium Sulfate Dihydrate (CaSO4·2H2O)

Muscovite Schist with Quartz

KAl2(AlSi3O10)(OH)2 in Schistose matrix

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Chalcedony (Agate/Chert)

Silicon Dioxide (SiO2)

Chalcedony (Agate)

Silicon Dioxide (SiO2)

Clear Quartz

Silicon Dioxide (SiO2)

Quartz (Milky/Clear variety)

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Chert (or Flint)

Chert (a cryptocrystalline variety of quartz, SiO2)

Greenstone / Glauconitic Siltstone

Metabasalt or Glauconite-rich Sedimentary Rock

Quartz Vein in Host Rock

Quartz (SiO2) in Mafic or Sedimentary Matrix

Pumice or Tufa/Travertine

Pumice (if igneous) or Calcareous Tufa (if sedimentary)

Chert (Flint)

Silicon Dioxide (SiO2)

Sandstone (River Pebble)

Arenite (SiO2 based)

Banded Chert (or Banded Jasper)

Silicon Dioxide (SiO2) with Iron Oxide impurities (Hematite/Goethite)

Sandstone (likely Quartzose)

Arenite (primarily SiO2)

Sandstone (Pebble)

Sandstone (arenite, arkose, wacke depending on composition)

Chert

Chert (microcrystalline quartz)

Gneiss

High-grade foliated metamorphic rock

Almandine Garnet in Schist

Almandine, Fe3Al2(SiO4)3