Organic Gemstone (Often Associated With Sedimentary Sequences)

Light-colored weathered rock fragment

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

Petrified Wood

Silicified wood (Quartz/Chalcedony - SiO2)

Blue Apatite

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

Serpentine (Serpentinite)

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

Chert (often called Flint)

Microcrystalline Quartz (SiO2)

Dalmatian jasper (often sold as Dalmatian stone)

Quartz-bearing leucocratic alkali-feldspar–aegirine/arfvedsonite porphyritic rock; commercial “jasper” designation

Rhodochrosite

Rhodochrosite (MnCO3)

Calcite crystal cluster (likely stalactitic or vein calcite)

Calcite, calcium carbonate (CaCO₃)

Chert (Flint)

Chert (Microcrystalline or cryptocrystalline Quartz - SiO2)

Yellow Jasper / Chert

Jasper (Silica/Quartz) - SiO2

Prehnite

Prehnite (Ca2Al(AlSi3O10)(OH)2)

Quartz vein in host rock

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

Amber

Succinite

Petrified Wood

Silicified wood / Permineralized wood (SiO2)

Chert (Jasper/Flint variant)

Silicon Dioxide (SiO2)

Weathered brown chert or silicified mudstone

Microcrystalline quartz (chalcedony), SiO₂; possibly a ferruginous silicified sediment

Yellow Jasper

Jasper (Silicon Dioxide, SiO2)

Red Chert (Jasper)

Silicon Dioxide (SiO2)

Carnelian Agate

Chalcedony (SiO2) with iron oxide inclusions

Chert (Yellow/Tan)

Microcrystalline Quartz (SiO2)

Chrysocolla

Hydrated copper silicate, (Cu,Al)2H2Si2O5(OH)4·nH2O

Chert (specifically Flint or Common Chert)

Silicon dioxide (SiO2) - Microcrystalline quartz

Carnelian

Silicon dioxide (chalcedony variety), SiO2

Banded Chert

Microcrystalline Quartz (SiO2)

Yellow Sapphire (Pukhraj)

Corundum (Al2O3)

Picture Jasper

Impure variety of silica (SiO2)

Turquoise

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

Fluorite

Calcium Fluoride (CaF2)

Turquoise

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

Rhodochrosite

Manganese carbonate (MnCO3)

Chert (often called Jasper in this color)

Microcrystalline quartz (SiO2)

Red Jasper

Silicon Dioxide (SiO2) with Hematite inclusions

Chert (Nodule)

Chert (composition: SiO2)

Fire Opal

Hydrated amorphous silica (SiO2·nH2O)

Larimar (with dendritic inclusions)

Blue Pectolite (NaCa2Si3O8(OH))

Chert (Jasper)

Silicon dioxide (SiO2)

Rhodonite

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

Jasper

Jasper / Silicon Dioxide (SiO₂)

Chert (specifically Tan Chert or Flint)

Silicon Dioxide (SiO2)

Chert (or Flint)

Chert (cryptocrystalline quartz), SiO2

Yellow Chert (Chert / Cryptocrystalline Quartz)

Silicon Dioxide (SiO2)

Chert (Flint Pebbles)

Microcrystalline or Cryptocrystalline Quartz (SiO2)