Sedimentary

Limestone with Calcite Crystals

Calcium Carbonate (CaCO3)

Sandstone (likely Fossilized Wood or Concrete Simulacrum)

Arenite / Silicified Wood / Anthropogenic Concrete

Fossiliferous Chert (with Brachiopod or Mollusk fragments)

Silicon dioxide (SiO2) with Calcium Carbonate (CaCO3) inclusions

Chert (Brecciated Chert)

Silicon Dioxide (SiO2)

River Cobble (Gneiss/Schist mix)

Foliated Metamorphic Rock (Gneissic/Schistose)

Druzy Quartz on Sandstone

Silicon Dioxide (SiO2) with Quartz Crystals on Clastic Sedimentary Rock

Ironstone (Limonite/Goethite Concretion)

Ferruginous Sedimentary Rock (composed of Goethite FeO(OH) and Limonite)

Bituminous Coal

Organic Sedimentary Rock (composed mostly of carbon with sulfur and hydrogen)

Sandstone with Liesegang Rings

Clastic Sedimentary Rock with Iron Oxide Precipitates (SiO2 + Fe2O3)

Red Sandstone

Clastic Terrigenous Sedimentary Rock (primarily SiO2 with Fe2O3 coating)

Ferruginous Sandstone (Ironstone)

Clastic sedimentary rock (SiO2 with Fe2O3/FeO(OH) cement)

Red Sandstone (Iron-rich Sandstone)

Clastic Sedimentary Rock - Quartz Arenite / Arkose with Hematite Cement

Ferruginous Sandstone

Clastic sedimentary rock (primarily Quartz with Iron Oxide cement)

Pyrite

Iron Sulfide (FeS2)

Glauconitic Sandstone

Glauconitic Quartz Arenite (with K,Mg,Fe,Al silicate hydroxide)

Glauconite

Glauconite (K,Na)(Fe3+,Al,Mg)2(Si,Al)4O10(OH)2

Chert

Microcrystalline Quartz (SiO2)

Banded Siltstone

Siltstone with planar bedding

Red Sandstone

Arenite (Ferruginous Sandstone)

Petrified Wood

Silicified Wood (primarily SiO2)

Ironstone concretion / Limonitic Sandstone

Goethite/Hematite Cemented Sandstone (Hydrated Iron Oxide)

Ironstone Concretion (Limonite/Goethite)

Ironstone (composed primarily of Goethite FeO(OH) and Limonite)

Chert / Flint

Microcrystalline Quartz (SiO2)

Ironstone Concretion (Limonite/Goethite)

Ironstone (primarily FeO(OH)·nH2O)

Polygenetic Conglomerate (Puddingstone)

Conglomerate (SiO2 matrix with mixed clasts)

Jasper (specifically a banded or dark variety)

Silicon Dioxide (SiO2) with impurities

Chert (White/Gray variety)

Chert (SiO2)

Concretion

Siderite or Ironstone Concretion

Petrified Wood

Silicified Wood (SiO2)

Fossilized Bone Fragment

Permineralized Vertebrate Fossil (Hydroxyapatite replaced by Minerals)

Chert (specifically Flint or Gray Chalcedony)

Microcrystalline Quartz (SiO2)

Fossilized Coprolite

Coprolite (fossilized feces)

Chert (Jasper/Iron-stained Quartzite)

Silicon Dioxide (SiO2)

Chert (and/or Flint)

Chert (Cryptocrystalline variety of Quartz, SiO2)

Pyrite Concretion (Grapestone)

Iron Sulfide (FeS2) Concretion

Petrified Wood

Silicified Wood (primarily SiO2)

Banded Chert

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Petrified Wood

Silicified Wood (SiO2)

Oolite or Oolitic Limestone

Oolitic Limestone (Principal mineral: Calcite, CaCO3)

Chert (Nodule/Pebble)

Chert (Silicon Dioxide, SiO2)

Chert (Flint variety)

Chert (Microcrystalline or Cryptocrystalline Quartz), SiO2

Chert (Jasper/Flint variety)

Microcrystalline Quartz (SiO2)