Marble

Fossil Coral (Rugose Coral)

Rugosa (extinct order); typically composed of Calcite (CaCO3) or replaced by Quartz (SiO2)

Glauconitic Sandstone (Greensand)

Glauconitic Quartz Arenite (Formula: (K,Na)(Fe,Al,Mg)2(Si,Al)4O10(OH)2)

Diamond

Diamond (C)

Sandstone (Ferruginous)

Arenite (primarily SiO2 with Fe2O3 staining)

Chert (Quartz Variety)

Chert (Silicon Dioxide, SiO2)

Chert pebble

Microcrystalline silica (SiO2)

Oolitic Ironstone

Sedimentary Ooidal Ironstone (Limonite/Hematite mixture)

Greywacke with Quartz Vein

Matrix: Impure Sandstone (SiO2 + varied clasts), Veins: Quartz (SiO2)

Diamond

Carbon (C)

Fossiliferous Limestone with Crinoid stems

Calcite-rich Biogenic Sedimentary Rock (CaCO3)

Fossilized Coral

Scleractinia (fossil order), primarily Calcium Carbonate (CaCO3)

Chert (often called Flint or River Stone)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Fossilized Echinoid (Sea Urchin)

Echinoidea (Class) - Often found as Micraster or Clypeaster specimens

Chert with Jasper/Quartz Inclusions

Silicon Dioxide (SiO2)

Amber

Succinite (Resin C10H16O)

Sandstone (likely Greywacke or Siltstone variety)

Arenite / Siltstone (primarily SiO2)

Limestone

Calcium Carbonate (CaCO3)

Ammonite Fossil

Ammonoidea (typically preserved as Calcite CaCO3 or Pyrite FeS2)

Orange Calcite

Calcium Carbonate (CaCO3)

Black Pearl (Tahitian-style Cultured Pearl)

Calcium Carbonate (Aragonite) with Conchiolin (CaCO3)

Fossilized Brachiopod

Phylum Brachiopoda (General mineral composition: Calcite/CaCO₃ or Silica/SiO₂)

Rough Diamond

Diamond (Native Carbon, C)

Serpentine

Antigorite, Lizardite, or Chrysotile (Mg,Fe,Ni,Al,Zn,Mn)2-3(Si,Al,Fe)2O5(OH)4

Sandstone (Water-worn Pebble)

Clastic Sedimentary Rock (primarily SiO2)

Iron-Stained Quartz Pebble

Silicon Dioxide (SiO2) with Iron Oxide (Limonite/Goethite) inclusions

Fossilized Horn Coral

Order Rugosa (Rugose Coral)

Sandstone (with Feldspathic/Arkose qualities)

Arenite (primarily SiO2 with KAlSi3O8 components)

Quartz Pebble

Silicon Dioxide (SiO2)

Fossilized Brachiopod Shell

Phylum Brachiopoda (likely Order Spiriferida or Strophomenida)

Chert (or Flint)

Chert (Sedimentary Cryptocrystalline Sio2)

Sandstone (Calcareous or Ferruginous)

Clastic sedimentary rock (SiO2 with CaCO3 or Fe2O3 cement)

Hag Stone

Siltstone or Fine-grained Sandstone with boring (e.g., Lithophaga impact)

Sandstone (Banded)

Clastic Sedimentary Rock (composed of SiO2, CaCO3, or Fe2O3 cement)

Chert (Nodule)

Silicon Dioxide (SiO2)

Chert (Jasper/Flint variant)

Silicon Dioxide (SiO2)

Yellow Calcite

Calcium Carbonate (CaCO3)

Limestone

Calcium Carbonate (CaCO3)

Chert

Chert (Microcrystalline Quartz, SiO2)

Chert (specifically Flint or Jasper variant)

Microcrystalline quartz (SiO2)

Chert (and Flint)

Microcrystalline Silica (SiO2)

Chert (Cherty Limestone / Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Yellow Jasper/Quartzite Pebble)

Microcrystalline Silicon Dioxide (SiO2)