Industrial Byproduct (Anthropogenic Material)

White Marble

Recrystallized Calcite (CaCO3)

Sandstone (with Iron Staining)

Clastic sedimentary rock (primarily Quartz with Hematite/Limonite oxides)

Sandstone

Arenite (primarily SiO2)

Fossil Plant Impression (Calamites)

Calamites sp. (Tracheophyta: Equisetopsida)

Zebra Jasper

Opaque microcrystalline Quartz (SiO2) with impurities

Cream River Jasper

Silicified microcrystalline quartz (SiO2)

Red Jasper

Silicon dioxide (SiO2) with iron oxide (Fe2O3) inclusions

Mixed Quartz and Jasper Pebbles

Silicon Dioxide (SiO2)

Natural or Cultured Pearl

Calcium Carbonate (Aragonite and Conchiolin), CaCO3

Jasper (Picture Jasper variety)

Silicon Dioxide (SiO2) with impurities

Chert (Jasper/Limonitic Chert)

Microcrystalline Quartz (SiO2)

Fossilized Shark Tooth (Basal Bone)

Otodus sp. (Mineralized Hydroxyapatite)

Chert Nodule (with Flint core)

Sedimentary Cryptocrystalline Quartz (SiO2)

Limonite (Gozzany Iron)

Limonite (FeO(OH)·nH2O)

Chert (containing Fossil Inclusions)

Microcrystalline Quartz (SiO2)

Diamond

Diamond (Pure Carbon - C)

Vesicular Basalt (commonly mistaken for Slag)

Scoriaceous Basalt (composed primarily of Plagioclase Feldspar and Pyroxene)

Chert (Nodule)

Microcrystalline or Cryptocrystalline Silica (SiO2)

Sandstone (likely Graywacke or Arkose variant)

Clastic Sedimentary Rock (SiO2 with assorted lithic fragments)

Chert (Nodular)

Microcrystalline Silica (SiO2)

Raw Diamond

Diamond (C)

Yellow Calcite

Calcium Carbonate (CaCO3)

Pumice

Pumice (Felsic volcanic rock)

Red Quartz

Silicon Dioxide (SiO2) with Hematite inclusions

Almandine Garnet & Tumbled Citrine Quartz

Fe3Al2(SiO4)3 (Garnet) and SiO2 (Quartz)

Quartz with Mica inclusion

Silicon Dioxide (SiO2) with Muscovite/Biotite inclusions

Garnet Schist

Almandine Garnet Schist

Diamond in Kimberlite

Diamond (C in Kimberlite)

Chert (and Chalcedony/Agate mixture)

Microcrystalline Quartz (SiO2)

Ventifact

Eolian Ventifact (often composed of basalt, chert, or quartzite)

Milky Quartz

Silicon Dioxide (SiO2)

Strawberry Quartz

Silicon Dioxide (SiO2) with Hematite or Goethite inclusions

Pink Polished Marble (or Limestone) Pillar

Recrystallized Calcium Carbonate (CaCO3)

Chert (Flint Pebbles)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (River Pebble)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert / Flint

Silicon Dioxide (SiO2)

Chert (Yellow or Ochre Jasper variant)

Microcrystalline Quartz (SiO2)

Quartz Crystal Cluster

Quartz (Silicon Dioxide, SiO2)

Coquina

Bioclastic Limestone (composed primarily of CaCO3)

Coquina

Coquina (Biogenic Limestone / CaCO3)

Chert / Flint Nodules

Cryptocrystalline Quartz (SiO2)

Banded Calcite (often sold as 'Travertine' or 'Mexican Onyx')

Calcium Carbonate (CaCO3)