Man Made Object (Coin)

Banded Calcite (often sold as 'Mexican Onyx')

Calcite (Calcium Carbonate - CaCO3)

Chert (often called Flint in archaeological contexts)

Silicon Dioxide (SiO2)

Diamond

Diamond (pure Carbon, C)

Sandstone (likely Quartzose)

Clastic sedimentary rock (SiO2 primary)

Chert (specifically Flint)

Chert (SiO2)

Rough Diamond

Pure Carbon (C)

Obsidian

Volcanic glass

Chert (Polished River Pebble)

Chert (SiO2)

Chert (Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Pearl

Biogenic Calcium Carbonate (Aragonite/Calcite), CaCO3

Pink Granite

Phaneritic Felsic Igneous Rock (composed of orthoclase, quartz, and plagioclase)

Sandstone (with potential Arkose/Lithic characteristics)

Arenite (Sedimentary rock composed of sand-sized grains)

Coquina

Biogenic Limestone (Calcite, CaCO3)

Coquina

Biogenic Limestone (Coquina)

Howlite (Dyed to resemble Turquoise)

Calcium Borosilicate Hydroxide (Ca2B5SiO9(OH)5)

Chert

Chert (SiO2)

Sandstone

Arenite (SiO2, often with CaCO3 or Fe2O3 cement)

Chert (Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Obsidian

Volcanic Glass (70-75% SiO2 with MgO and Fe3O4)

Corundum (Sapphire variant)

Aluminium oxide (Al2O3)

Fossilized Gastropod (Snail)

Class Gastropoda (internal mold or 'steinkern')

Jade

Jadeite or Nephrite

Red Sandstone

Arenite (Ferruginous Sandstone)

Red Jasper

Silicon Dioxide (SiO2) with Hematite impurities

Charoite

Charoite (Hydrated potassium sodium calcium barium strontium silicate hydroxyfluoride)

Blue Chalcedony

Chalcedony (a cryptocrystalline variety of Quartz - SiO₂)

Nephrite Jade

Ca2(Mg, Fe)5Si8O22(OH)2

Granite

Phaneritic Felsic Igneous Rock

Granite

Granite (a phaneritic intrusive igneous rock)

Granite

Phaneritic Igneous Rock (composed mostly of Quartz, Feldspar, and Mica)

Lapis Lazuli

Lazurite-rich metamorphic rock; (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2

Amber

Succinite (organic mineraloid); Chemical formula: C10H16O

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2)

Jasper

Jasper (Silicon Dioxide, SiO2)

Banded Agate (specifically Carnelian Agate)

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Lapis Lazuli

Na8(Al6Si6O24)S2 (composed primarily of Lazurite, Calcite, and Pyrite)

Sodalite

Sodalite (Na8(Al6Si6O24)Cl2)

Dalmatian Stone (often misnamed Dalmatian Jasper)

Aplite (with hornblende/arfvedsonite inclusions)

Snowflake Obsidian

Volcanic glass with Cristobalite inclusions (70–75% SiO2)

Granite

Granite (Silicic Intrusive Igneous Rock)

Granite

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

Jasper (Iron-rich Chalcedony)

Jasper (Microcrystalline Silicon Dioxide, SiO2 plus iron oxide impurities)