Organic Gemstone (Not A Rock Or Mineral)

Chert (specifically Flint or Jasper variant)

Microcrystalline Quartz (SiO2)

Chert (often called Flint)

Chert (Microcrystalline or cryptocrystalline Silica, SiO2)

Chert (specifically Red Chert or Jasper)

Microcrystalline Quartz (SiO2)

Chert (Brecciated or Veined)

Silicon Dioxide (SiO2)

Amber

Succinite (with empirical formula approximately C10H16O)

Amazonite

K(AlSi3O8) - Lead-bearing Microcline (Potassium Feldspar)

Limestone with Chert or Siltstone bands

Sedimentary carbonate rock (CaCO3) often with siliceous impurities

Graphite-veined Quartzite

Meta-sedimentary Quartzite with Carbonaceous/Graphitic Inclusions (SiO2 + C)

Chert (specifically Flint)

Microcrystalline Quartz (SiO2)

Tiger's Eye (Unpolished)

Pseudomorph of Quartz after Crocidolite (SiO2)

Chert (variations include Flint or Jasper)

Cryptocrystalline Quartz (SiO2)

Chert / Flint

Chert (Microcrystalline Quartz, SiO2)

Red Jasper

Silicon Dioxide (SiO2) with Iron Oxide inclusions

Amber

Succinite (specifically for Baltic amber); chemical formula approx. C10H16O

Pearl

Aragonite / Calcium Carbonate (CaCO3)

Chert / Flint

Chert (varieties include Flint)

Turquoise in Matrix

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

Chert (Nodule/Pebble)

Chert (Silicon Dioxide, SiO2)

Chert (specifically Flint or Dark Chert)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Nodule)

Silicon Dioxide (SiO2)

Petrified Wood

Silicified Wood (SiO2)

Lapis Lazuli (Raw Ore)

Na8[Al6Si6O24]n(S,Cl,SO4,OH)2 (Lazurite component)

Fossil Coral (Rugose Coral Fragment)

Rugosa (extinct order of solitary and colonial corals)

Clear Quartz

Silicon Dioxide (SiO2)

Amethyst

Silicon Dioxide (SiO2) with iron impurities

Sodalite

Sodalite (Na8Al6Si6O24Cl2)

Red Jasper

Silicon Dioxide (SiO2) with Hematite inclusions

Milky Quartz

Silicon Dioxide (SiO2)

Black Opal

Hydrated Amorphous Silica (SiO2·nH2O)

Amethyst

Silicon Dioxide (SiO2) with iron impurities

Green Aventurine

Silicon Dioxide (SiO2) with inclusions

Druzy Quartz on Milky Quartz

Silicon Dioxide (SiO2)

Chert (Nodule / Geode fragment)

Microcrystalline Quartz (SiO2)

Turquoise

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

Sodalite

Sodalite (Na8(Al6Si6O24)Cl2)

Quartz (Milky/Clear variety)

Silicon Dioxide (SiO2)

Fossilized Shell in Limestone

Bivalve fossil (CaCO3) in Carbonate Sedimentary Rock

Black Opal

Hydrated Silica (SiO2·nH2O)

Bituminous Coal

Organic sedimentary rock (humic coal)

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2)

Petrified Wood

Silicified Wood (SiO2)

Shungite

Non-crystalline carbon (similar to anthracite coal or meta-anthracite)