Organic Gemstone (Often Associated With Sedimentary Sequences)

Red Sandstone

Arenite (with Iron Oxide / Hematite cementation)

Limestone (Concretionary or Tufa)

Calcium Carbonate (CaCO3)

Precious Red Coral

Corallium rubrum / Corallium japonicum

Chert (Common Opal/Chalcedony)

Microcrystalline Quartz (SiO2)

Petrified Wood

Silicified wood (primarily Silicon Dioxide, SiO2)

Jasper with Agate and Quartz Inclusions

Silicon Dioxide (SiO2) - Chalcedony / Quartz aggregate

Sandstone Concretion

Clastic sedimentary rock (primarily Quartz SiO2)

Banded Chert

Sedimentary Cryptocrystalline Quartz (SiO2)

Aquamarine

Beryl (Be3Al2Si6O18)

Moonstone

Orthoclase Feldspar (KAlSi3O8)

Petrified Wood

Silicified Wood (SiO2)

Dendritic Agate (specifically Orange/Tumbled)

Silicon Dioxide (SiO2) with Oxide Inclusions

Chert (Green variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Amber / Fossilized Resin

Succinite / Fossilized Tree Resin

Prehnite

Prehnite, Ca2Al2Si3O10(OH)2

Carnelian

Carnelian (a variety of Chalcedony, SiO2)

Chert (Jasper/Flint variety)

Microcrystalline Quartz (SiO2)

Chert (Yellow Jasper/Flint)

Microcrystalline Quartz (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Chert (varieties include Flint or Jasper)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert / Flint

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Fossiliferous Limestone

Biogenic Limestone (Calcium Carbonate, CaCO3)

Chert (Nodule)

Microcrystalline quartz (SiO2)

Amber

Amber (C10H16O)

Gneiss

Foliated Metamorphic Rock (Gneiss)

Chert (Iron-Stained)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Beryllonite

Beryllonite (NaBePO4)

Pyrite in Shale

Iron Disulfide (FeS2) in Argillaceous Shale

Chert (and/or Flint)

Microcrystalline Quartz (SiO2)

Chert Pebble

Microcrystalline Quartz (SiO2)

Chert (specifically Pink Chert or Jasperized Chert)

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Chert (often called Flint in this variation)

Silicon dioxide (SiO2) - Microcrystalline quartz

Glauconitic Sandstone (Greensand)

Glauconitic Quartz Arenite (containing Glauconite, (K,Na)(Fe3+,Al,Mg)2(Si,Al)4O10(OH)2)

Fossiliferous Limestone (Coquina / Shell Limestone)

Bioclastic Limestone (CaCO3)

Shale with Vein Infillings

Shale (a fine-grained clastic sedimentary rock). The veins could be Calcite (CaCO3), Quartz (SiO2), or other minerals.

Green Fluorite

Calcium Fluoride (CaF2)

Fossil Shark Tooth (Sand Tiger or Mackerel Shark)

Carcharias sp. or Otodus sp. replaced by Hydroxylapatite/Calcium Carbonate

Petrified Wood (Silicified Wood)

Silicified Paleoflora (mainly Quartz, SiO2)

Garnet Rhyolite

Rhyolite (high-silica volcanic rock) with almandine/spessartine garnet

Amber

Succinite

Pyrite

Pyrite (FeS2)

Petrified Wood

Silicified Wood (primarily SiO2 - Silicon Dioxide)