Organic Gemstone (Often Associated With Sedimentary Sequences)

Chert / Flint

Chert (Cryptocrystalline Quartz, SiO2)

Jasper

Silicon dioxide (SiO2)

Chert (with Limonite staining)

Microcrystalline Quartz (SiO2)

Chert (specifically Brown Chert or Flint)

Cryptocrystalline Quartz (SiO2)

Chert (Flint)

Microcrystalline Silica (SiO2)

Fossiliferous Limestone (Coquina)

Biogenic Limestone (Calcium Carbonate, CaCO3)

Chert (Yellow Jasper)

Microcrystalline Quartz (SiO2)

Chert (Arrowhead/Tool variety)

Microcrystalline Quartz (SiO2)

Fossilized Shark Tooth (Fragment)

Elasmobranchii fossil (likely Cretalamna or Squalicorax genus)

Rhodonite

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

Chert (Polished Gemstone / River Stone)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Fossiliferous Shale

Laminated Mudrock with plant fossils

Quartz Geode (Citrine or Iron-stained Quartz)

Silicon Dioxide (SiO2)

Gold Nugget

Native Gold (Au)

Petrified Wood

Silicified Wood (SiO2)

Lazulite

Lazulite (MgAl2(PO4)2(OH)2)

Amber

(C10H16O)n – an amorphous organic substance, primarily composed of polymerized isoprenoids.

Chert (River Cobble)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Chert (specifically Gray/Tan Chert Node)

Microcrystalline Quartz (SiO2)

Orthoceras Fossil Limestone

Orthoceras (extinct Cephalopod fossil) in Matrix

Coquina / Shelly Limestone

Coquina (Biogenic Limestone)

Smoky Quartz with Siderite and Pyrite

Silicon Dioxide (SiO2) with Ferrous Carbonate (FeCO3) and Iron Sulfide (FeS2)

Stardust (Micrometeorite)

Chondrite / Micrometeorite (Extraterrestrial Silicate)

Chert (Smooth River Pebble)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Turquoise

CuAl6(PO4)4(OH)8·4H2O

Chert (Limestone-based)

Silicon dioxide (SiO2)

Chert (with Quartz vein/coating)

Microcrystalline Quartz (SiO2)

Chert (Yellow Jasper variant)

Microcrystalline Quartz (SiO2)

Fossilized Coral

Scleractinia (fossil order), primarily Calcium Carbonate (CaCO3)

Chert (Jasper variety)

Cryptocrystalline Quartz (SiO2)

Chert (Flint variety)

Silicon Dioxide (SiO2)

Coral Rock (Coquina)

Biogenic Limestone (Calcium Carbonate - CaCO3)

Chert (Flint variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (variations include Flint/Jasper)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Agate (Chert/Chalcedony)

Silicon Dioxide (SiO2)

Jasper (Green variety)

SiO2 (Silicon Dioxide with iron/chlorite inclusions)

Chert (Quartz Variety)

Chert (mostly SiO2 / Silicon Dioxide)

Peach Moonstone

Orthoclase Feldspar (KAlSi3O8)

Anthracite Coal

Anthracite (Carbon)

Chinese Writing Stone

Porphyritic Basalt or Porphyritic Andesite

Chrysocolla in Quartz (Gem Silica)

Cu2-xAlx(H2-xSi2O5)(OH)4·nH2O (Chrysocolla) / SiO2 (Quartz)

Red Jasper

Jasper (a cryptocrystalline variety of Quartz, SiO₂)