Organic Gemstone (Often Associated With Sedimentary Sequences)

Green Fluorite

Calcium Fluoride (CaF2)

Banded Chert

Microcrystalline Quartz (SiO2)

Amber

Succinite (Fossilized Tree Resin, C10H16O)

Rhodonite

Manganese Inosilicate (Mn,Fe,Mg,Ca)SiO3

Chert (Black Chert/Flint)

Silicon Dioxide (SiO2)

Light-colored weathered rock fragment

Likely limestone or calcareous sandstone; exact identification is uncertain from the photograph

Amazonite

Microcline (KAlSi3O8) with lead impurities

Petrified Wood

Silicified wood (Quartz/Chalcedony - SiO2)

Rhodochrosite

Rhodochrosite (MnCO3)

Amber

Succinite

Carnelian Agate

Chalcedony (SiO2) with iron oxide inclusions

Serpentine (Serpentinite)

Antigorite, Lizardite, or Chrysotile; (Mg,Fe)3Si2O5(OH)4

Quartz vein in host rock

Quartz (SiO₂), likely in a weathered carbonate or sedimentary matrix

Chalcopyrite

Copper Iron Sulfide (CuFeS2)

Amazonite

Microcline Feldspar (KAlSi3O8)

Calcite crystal cluster (likely stalactitic or vein calcite)

Calcite, calcium carbonate (CaCO₃)

Fossiliferous limestone with possible ammonite or shell impressions

Calcitic limestone, chiefly CaCO₃; fossils may include ammonoids or bivalves

Rhodonite

Rhodonite (Mn,Fe,Mg,Ca)SiO3

Carnelian (Chalcedony)

Silicon Dioxide (SiO2)

Chert (specifically Red Chert / Jasper)

Silicon Dioxide (SiO2)

Black Pearl (Tahitian Pearl)

Aragonite / Calcite (CaCO3) with Conchiolin

Chert (Blue-Gray Chert)

Microcrystalline quartz (SiO2)

Jasper

Silicon Dioxide (Microcrystalline Quartz, $SiO_2$)

Jasper

Jasper (Silicon Dioxide) - SiO2

Blue Apatite

Apatite - Ca5(PO4)3(F,Cl,OH)

Turquoise

Hydrated phosphate of copper and aluminium (CuAl6(PO4)4(OH)8·4H2O)

Chert (Quartz Variety)

Microcrystalline Silica (SiO2)

Chert (Yellow Jasper variant)

Microcrystalline Quartz (SiO2)

Ferruginous Sandstone

Sandstone with Iron Oxide (Limonite/Goethite)

Yellow Jasper

Jasper (Silicon Dioxide, SiO2)

Carnelian

Silicon dioxide (chalcedony variety), SiO2

Chert (often called Flint)

Microcrystalline Quartz (SiO2)

Chert (var. Jasper)

Microcrystalline Quartz (SiO2)

Green Fluorite

Fluorite (Calcium Fluoride, CaF2)

Polished red jasper

Jasper, an opaque microcrystalline variety of quartz (SiO₂), colored mainly by iron oxides

Rhodochrosite

Manganese carbonate (MnCO3)

Chert (or Flint)

Chert (cryptocrystalline quartz), SiO2

Prehnite

Prehnite (Ca2Al(AlSi3O10)(OH)2)

Chert (Yellow/Tan)

Microcrystalline Quartz (SiO2)

Turquoise

Hydrated phosphate of copper and aluminium [CuAl6(PO4)4(OH)8·4H2O]

Yellow Jasper

Silicon Dioxide (SiO2) with iron oxide inclusions

Red Chert (Jasper)

Silicon Dioxide (SiO2)