Organic Gemstone (Not A Rock Or Mineral In The Traditional Sense, But Bio Mineralized Material)

Petrified Wood

Silicon Dioxide (SiO2) - Calcified / Silicified Wood

Chalcedony (Agatized Coral / Rough Chalcedony Node)

Silicon Dioxide (SiO2)

Petrified Wood

Silicified wood (Quartz, SiO2)

Sandstone (Ferruginous)

Arenite (SiO2 with iron oxide impurities)

Chert (varieties include Flint and Jasper)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Glauconitic Sandstone

Glauconitic Sandstone (contains (K,Na)(Fe,Al,Mg)2(Si,Al)4O10(OH)2)

Chrysocolla

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

Sandstone

Quartz Sandstone (predominantly)

Amber

Succinite (Approximate formula: C10H16O)

Sandstone (Picture Sandstone)

Arenite (primarily SiO2)

Chert (often found as Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Petrified Wood

Silicified wood (Quartz/Chalcedony/Opal replacing organic matter)

Quartz Geode

Silicon Dioxide (SiO2) in Host Rock

Pyrite in Shale

Iron Disulfide (FeS2)

Limonite (Iron Ore)

Limonite (Hydrous iron(III) oxide-hydroxide mixture, primarily FeO(OH)·nH2O)

Petrified Wood (Agatized/Silicified Wood)

Silicified Wood / Chalcedony (SiO2)

Shale or Slaty Mudstone

Argillaceous sedimentary rock

Pearl

Organic gemstone (Calcium carbonate / CaCO3 + Conchiolin)

Sandstone (with potentially high Feldspar/Arkose content)

Clastic sedimentary rock (SiO2 dominated)

Banded Chert

Microcrystalline Quartz (SiO2)

Chert (Jasper/Common Opal mix)

Microcrystalline Quartz (SiO2)

Limestone with Calcite Veins

Calcium Carbonate (CaCO3)

Sandstone (likely Quartzose Sandstone pebble)

Arenite (primarily SiO2)

Septarian Nodule

Septarian Concretion (CaCO3 with Siderite/Limonite streaks)

Agatized Fossil (Druzy Agate)

Silicon Dioxide (SiO2) replacing organic matter

Black Marble

Recrystallized Calcite (CaCO3)

Chert (often called Jasper in this color variety)

Microcrystalline Quartz (SiO2)

Fossilized Wood (with Coal and Limonite)

Petrified Wood (Silicified or Carbonized Flora)

Chert (variant Flint/Jasper)

Microcrystalline Opaline Silica (SiO2)

Sandstone (with Lichen)

Arenite (primarily SiO2)

Chert / Flint

Chert (varietal name for microcrystalline quartz). Chemical formula: SiO₂

Cherry Creek Jasper (also known as Red Creek Jasper or Cherry Creek Agate)

Jasper, microcrystalline quartz (SiO₂)

Ironstone Concretion (Ironstone Gourd)

Limonite/Goethite Concretion (FeOO(H))

Quartz Geode

Silicon Dioxide (SiO2)

Quartz Vein in River Siltstone

Crystalline Quartz (SiO2) in Siliclastic Matrix

Olivine (Peridot)

Magnesium Iron Silicate (Mg,Fe)2SiO4

Pearl

Aragonite / Calcium Carbonate (CaCO3)

Blue Apatite

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

Amber (in Matrix/Shale)

Amber (Fossilized Tree Resin)

Bauxite

Bauxite (Mixture of Al(OH)3, AlO(OH), and Fe2O3)

Sandstone (with Concretion)

Arenite / Quartzose Sandstone

Quartz (Milky or Iron-Stained)

Silicon Dioxide (SiO2)