Sedimentary (Biogenic)

Limestone

Calcium Carbonate (primarily CaCO3 as Calcite or Aragonite)

Sandstone (likely Fossilized Wood or Concrete Simulacrum)

Arenite / Silicified Wood / Anthropogenic Concrete

Chert (Brecciated Chert)

Silicon Dioxide (SiO2)

Limestone

Calcium Carbonate (CaCO3)

Limestone with Calcite Crystals

Calcium Carbonate (CaCO3)

Fossiliferous Chert (with Brachiopod or Mollusk fragments)

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

Bituminous Coal

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

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)

Sandstone (specifically Cross-bedded Sandstone)

Arenite (composed primarily of SiO2)

Chert (Smooth River Pebble)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Gypsum (Wallboard/Drywall)

Calcium Sulfate Dihydrate (CaSO4·2H2O)

Ferruginous Sandstone (Iron-rich Sandstone)

Ferruginous Arenite

Chert (Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Flint Nodules)

Chert (Microcrystalline Quartz, SiO2)

Yellow Jasper

Silicon Dioxide (SiO2)

Chert (Banded Variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Gastropod Fossil (Snail Internal Mold)

Gastropoda; internal mold (steinkern), often composed of Calcium Carbonate (CaCO3) or Silica (SiO2)

Chert (Grey-Green Flint)

Microcrystalline silicon dioxide (SiO2)

Limonite (Ironstone Concretion)

Limonite (Hydrated iron(III) oxide-hydroxide, mixtures of FeO(OH)·nH2O)

Chert (White Chert / Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Belemnite (Fossilized Rostrum)

Belemnitida (Order), composed of Calcite (CaCO3)

Ammonite Fossil (Polished Half)

Ammonoidea (subclass)

Fossil Shell (Bivalve)

Class Bivalvia (Likely a member of the Ostreidae or Gryphaeidae family), CaCO3

Chert (Nodule)

Cryptocrystalline Silica (SiO2)

Sandstone

Arenite (primarily SiO2)

Chert (specifically White Chert or Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Sandstone

Arenicola (comprising mostly Quartz, SiO2)

Chert (Flint)

Chert (microcrystalline quartz)

Chert (or Flint)

Silicon dioxide (SiO2)

Chert (Flint nodule)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Dalmatian Jasper

Peralkaline rhyolite

Ferruginous Sandstone

Sandstone, Iron-rich

Chert (Brown variety / Common Jasper)

Microcrystalline Quartz (SiO2)

Red Sandstone

Arenite with Hematite cementation

Belemnite Fossil (Guard)

Belemnoidea (Carbonate/Calcite replacement)

Limonite Concretion

Hydrated iron(III) oxide-hydroxide (FeO(OH)·nH2O)

Petrified Wood

Silicified wood (Quartz variant, SiO2)

Petrified Wood

Silicified Wood (primarily SiO2)

Sandstone

Arenite (primarily SiO2)