Man Made Byproduct (Often Mistaken For Obsidian Or Emerald)

Fossil Brachiopod Cast (Atrypa species)

Phylum Brachiopoda, Class Rhynchonellata, Order Atrypida

Chert (Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Dumortierite Quartz

Al7BO3(SiO4)3O3 (Aluminum borate silicate)

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Apache Tears (Obsidian)

Volcanic Glass (SiO2 - Silicon Dioxide with impurities)

Ferruginous Quartzite (Chert)

Quartzite with Iron inclusions (SiO2 + Fe2O3)

Ferruginous Siltstone or Mudstone

Ferruginous Siltstone / Goethitic Sandstone

Banded Sandstone

Arenite (with iron oxide banding)

Quartzite Cobble

Meta-quartzite (SiO2)

Apache Tear

Hydrated Obsidian (Volcanic Glass)

Mahogany Obsidian

Obsidian (Volcanic Glass) with Hematite/Magnetite inclusions

Snowflake Obsidian

Vitreous volcanic silicate rock (SiO2) with Spherulite inclusions

Sodalite

Sodalite, Na8(Al6Si6O24)Cl2

Granite

Granite (phaneritic intrusive igneous rock consisting of quartz, feldspar, and mica)

Green Aventurine

Aventurine Quartz (SiO2 with inclusions of Fuchsite mica)

Blue Quartzite

Blue Quartzite (Primary mineral: Quartz, SiO2 with magnesio-riebeckite or crocidolite inclusions)

Scoria (Lava Rock)

Mafic extrusive volcanic rock (Scientific formula varies based on mineral content: primarily SiO2, MgO, and FeO)

Siltstone

Siltstone (primarily SiO2 with Al2O3)

Ferruginous Quartz (Iron-Stained Quartz)

Silicon Dioxide (SiO2) with Iron Oxide inclusions

Mahogany Obsidian

Obsidian (volcanic glass with Hematite/Magnetite inclusions)

Ferruginous Sandstone (Gozzan/Ironstone)

Arenite with Limonite/Goethite cement (FeO(OH)·nH2O)

Quartzite (Potentially Ferruginous)

Quartzite (SiO2)

Red Quartz (Ferruginous Quartz)

Silicon Dioxide with Hematite inclusions (SiO2 + Fe2O3)

Chalk

CaCO3 (primarily Calcium Carbonate), biogenic sedimentary rock

Moonstone (specifically Rainbow Moonstone / White Labradorite)

White Labradorite (Feldspar Group: (Na,Ca)(Al,Si)4O8)

Snowflake Obsidian

Volcanic Glass with Cristobalite inclusions

Diorite

Intermediate plutonic igneous rock

Black Spinel

Magnesium Aluminum Oxide (MgAl2O4)

Sodalite

Sodalite (Na8(Al6Si6O24)Cl2)

Quartzite

Quartzite (primarily SiO2)

Flesh-toned Siltstone

Siltstone (composed of microscopic Quartz and Feldspar grains)

Mahogany Obsidian

Volcanic Glass with Hematite/Magnetite inclusions

Chert / Flint

Silicon Dioxide (SiO₂)

Lapis Lazuli

A metamorphic rock primarily composed of lazurite (Na,Ca)8[(S,SO4,Cl)2|(Al6Si6O24)], calcite (CaCO3), and pyrite (FeS2).

Chert (often called Flint)

Chert (SiO2)

Ferruginous Sandstone with Ironstone Concretion

Goethite-rich Sandstone (FeO(OH))

Iron-stained Quartz

Silicon Dioxide (SiO2) with Limonite/Hematite inclusions

Diorite

Phaneritic Intrusive Igneous Rock (composed of Plagioclase feldspar, Hornblende, and Biotite)

Sandstone (likely Fossilized Wood or Concrete Simulacrum)

Arenite / Silicified Wood / Anthropogenic Concrete

Chert (Flint)

Microcrystalline Quartz (SiO2)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Arfvedsonite in Quartz

Arfvedsonite [Na3(Fe2+4Fe3+)Si8O22(OH)2] often hosted in Quartz or Feldspar