Organic Gemstone (Not A Mineral)

Petrified Wood

Silicified Wood (SiO2)

Fossilized Brain Coral

Diploria labyrinthiformis (Fossilized)

Chert (often called Flint)

Chert (Microcrystalline Silicon Dioxide, SiO2)

Olivine (Peridot)

Magnesium Iron Silicate (Mg,Fe)2SiO4

Garden Quartz

Included Quartz (SiO2 with accessory minerals such as Chlorite, Hematite, or Feldspar)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Yellow Sapphire or Citrine

Al2O3 (Corundum) or SiO2 (Quartz)

Moonstone

Potassium Aluminum Silicate (KAlSi3O8)

Chert (often called Flint or Jasper)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Fairburn Agate

Cryptocrystalline Quartz (SiO2)

Chert (Jasper variety)

Silicon Dioxide (SiO2)

Rhodochrosite

Manganese carbonate (MnCO3)

Picture Jasper

Silicon Dioxide (SiO2) - Opaque Chert/Quartzite variety

Carnelian and White Quartz Bracelet

Silicon Dioxide (SiO2) - specifically Carnelian (Chalcedony) and Rock Crystal/Snow Quartz

Petrified Wood

Silicified Wood (SiO2)

Petrified Wood

Silicified Wood (SiO2)

Orthoceras Fossil in Limestone

Orthoceras (extinct genus of cephalopods) in Carboniferous or Devonian Limestone

Petrified Wood

Silicified wood (Quartz/Chalcedony/Opal)

Chert (Jasper/Limonitic Chert)

Microcrystalline Quartz (SiO2)

Petrified Wood

Silicified Wood (SiO2)

Petrified Wood

Silicified Wood (SiO2)

Sulfidic Mudstone with Pyrite/Goethite

Sulfidic Siltstone/Mudstone (FeS2)

Fossilized Crinoid Stem Segment

Crinoid (Phylum Echinodermata, Class Crinoidea)

Dinosaur Skull Fossil (Velociraptor Replica)

Velociraptor mongoliensis fossil specimen in sedimentary matrix

Ferruginous Chert

Microcrystalline Quartz (SiO2) with Iron Oxides

Petrified Wood

Silicified wood (primarily SiO2)

Petrified Wood (Agatized/Silicified Wood)

Silicified Paleoxylon (primarily SiO2)

Chert (and Chalcedony)

Microcrystalline Quartz (SiO2)

Petrified Wood

Silicified Wood (SiO2)

Limestone (Concretionary or Tufa)

Calcium Carbonate (CaCO3)

Fossil Coral (Rugosa or Solitary Coral)

Rugosa (Order), often referred to as 'Horn Coral' (Lithostrotionella or Grewingkia)

Chert (Holey Stone)

Microcrystalline Quartz (SiO2)

Citrine

Quartz (SiO₂) variety

Petrified Wood

Silicified Wood (primarily SiO2)

Banded Chert

Cryptocrystalline Quartz (SiO2)

Sandstone (likely Fossilized Wood or Concrete Simulacrum)

Arenite / Silicified Wood / Anthropogenic Concrete

Red Jasper

Cryptocrystalline Quartz (SiO2 with Iron oxide inclusions)

Petrified Wood

Silicified Wood (SiO2)

Septarian Nodule or Mud Crack Fossil

Septarian Nodule (Concretion)

Sandstone Concretion

Sedimentary Clastic Rock (Silicate-rich)

Petrified Wood

Silicified Wood (SiO2)

Pyrite Geode (Sparkling Druzy)

Iron Sulfide (FeS2) in Sedimentary Nodule