Man Made Object (Metalwork)

Chert (Iron-stained)

Chert (Microcrystalline and Cryptocrystalline Quartz, SiO2)

Diamond in Kimberlite

Diamond (C in Kimberlite Matrix)

Clear Quartz

Silicon Dioxide (SiO2)

Chert (Flinty variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chalk

Calcium Carbonate (CaCO3)

Desert Rose (also known as Sand Rose)

Gypsum (CaSO4·2H2O) or Barite (BaSO4) with sand inclusions

Chert (and associated river cobbles)

Silicon dioxide (SiO2)

Quartzite

Quartzite (SiO2)

Crinoid Fossil Stem Segment

Class Crinoidea (Echinodermata)

Banded Calcite (often commercially sold as 'Mexican Onyx' or 'Honey Onyx')

Calcite (Calcium Carbonate, CaCO3)

Pyrite (Fool's Gold)

Iron Disulfide (FeS2)

Chert (varieties include Flint and Jasper)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Amethyst

Amethyst (Silicon Dioxide, SiO2 + Fe4+ impurities)

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2)

Amethyst

Quartz (SiO2) with trace iron impurities

Petrified Wood

Silicified wood (Quartz/Chalcedony)

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2)

Red Jasper

Argillaceous microcrystalline quartz (SiO2 with Fe2O3 inclusions)

Snowflake Obsidian (or similar porphyritic volcanic rock)

Obsidian with Spherulites (if glassy), or Porphyritic Rhyolite/Andesite (if crystalline groundmass)

Yellow Jasper

Silicon Dioxide (SiO2) with iron inclusions

Jasper (Banded Jasper)

Silicon Dioxide (SiO2) with impurities

Fluorite

Calcium Fluoride (CaF2)

Anthracite Coal

Anthracite (Carbon-rich metamorphic coal)

Smoky Quartz (with possible Feldspar inclusions)

Silicon Dioxide (SiO2)

Green Aventurine

Aventurine (a variety of Quartz, SiO2)

Blue Chalcedony

Chalcedony (Silicon Dioxide, SiO2)

Orange Calcite (Polished Sphere)

Calcium Carbonate (CaCO3)

White Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Pyrite

Iron Sulfide (FeS2)

Chert (Nodular or Massive Variety)

Cryptocrystalline Quartz (SiO2)

Angel Aura Quartz (Treated Clear Quartz)

Silicon Dioxide (SiO2) coated with Vaporized Silver and Platinum

Chert (variations include Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Grey-Green Flint)

Microcrystalline silicon dioxide (SiO2)

Banded Jasper

Silicon Dioxide (SiO2)

Rutilated Quartz (likely Citrine or Smoky Quartz with Rutile inclusions)

SiO2 with TiO2 inclusions (Quartz with Rutile)

Chrysoprase

Chrysoprase (a variety of Chalcedony, SiO₂)

Specular Hematite (Specularite)

Iron Oxide (Fe2O3)

Silver Sheen Obsidian

Volcanic Glass (Amorphous Silicon Dioxide - SiO2 with impurities)

Clear Quartz (Rock Crystal)

Quartz (Silicon Dioxide, SiO2)

Granodiorite with Quartz Veining

Granodiorite (containing Plagioclase Feldspar, Quartz, and Biotite/Hornblende) with Quartz (SiO2) veins

Smurf Rock (Fictional Interpretation)

Cyanus Anthropomorphicus (Geologic Simulation)