Man Made Object (Coin)

Granodiorite

Granodiorite (Quartz + Plagioclase + Alkali Feldspar + Biotite/Hornblende)

Chert (Flint)

Silicon Dioxide (SiO2)

Chert (Yellow/Tan variety)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Sandstone

Clastic sedimentary rock (primarily SiO2)

Banded Chert

Microcrystalline Quartz (SiO2)

Bivalve Fossil (Shell Fragment)

Class Bivalvia (Calcium Carbonate - CaCO3)

Amethyst

Amethyst (Silicon Dioxide - SiO2 with Iron impurities)

Blue Chalcedony

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Rhodonite

Manganese Silicate (Mn, Fe, Mg, Ca)SiO3

Coquina

Bioclastic Limestone (composed primarily of CaCO3)

Coquina / Fossiliferous Limestone

Calcareous bioclastic sedimentary rock (CaCO3)

Nephrite Jade

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

Yellow Calcite

Calcium Carbonate (CaCO3)

Agate Geode

Chalcedony (cryptocrystalline SiO2)

Diorite (Gneissic)

Diorite

Pearl

Aragonite (CaCO3) with Conchiolin

Diabase (Greenstone)

Diabase (Dolerite)

White Jade (Nephrite)

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

Spondylus Oyster Calcification / Fossilized Oyster

Spondylus (Thorny Oyster) / Calcium Carbonate (CaCO3)

Smoky Quartz

Smoky Quartz (Silicon Dioxide - SiO2)

Coquina (Fossiliferous Limestone)

Biogenic Limestone (Calcium Carbonate, CaCO3)

Sandstone

Arenite (composed primarily of SiO2)

Sandstone (Ferruginous)

Arenite (SiO2 with Fe2O3 inclusions)

Sandstone

Arenite (composed primarily of SiO2)

Lapis Lazuli

Lapis Lazuli (a rock, not a single mineral; primary mineral is Lazurite (Na,Ca)8(AlSiO4)6(S,SO4,Cl)1-2

Pearl

Pearl (Calcium Carbonate with organic conchiolin, CaCO3)

Chert (with Limestone matrix)

Silicon dioxide (SiO2)

Moonstone

Orthoclase Feldspar ((K,Na)AlSi3O8) with Albite inclusions

Chert (and/or Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (variations include Flint/Jasper)

Cryptocrystalline Quartz (SiO2)

Smoky Quartz

Silicon Dioxide (SiO2)

Diorite

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

Silver (Jewelry form)

Native Silver (Ag)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Chert / Jasper

Silicon Dioxide (SiO₂)

Ruby Fuchsite / Ruby in Fuchsite

Ruby (Al2O3 variety corundum) and Fuchsite (K(Al,Cr)2AlSi3O10(OH)2 - a chromium-rich variety of muscovite mica) in Quartz matrix

Red Jasper (Skull Carving)

Jasper (Silicon Dioxide, SiO2 plus Iron Oxide inclusions)

Agate

Agate (Silicon Dioxide, SiO2)

Rhodonite

Rhodonite (Manganese Iron Magnesium Calcium Silicate - (Mn,Fe,Mg,Ca)SiO3)

Mahogany Obsidian

Volcanic glass containing Magnetite/Hematite

Pink Dyed Agate (Pink Agate Slice)

Silicon Dioxide (SiO2) - Chalcedony / Cryptocrystalline Quartz

Rhodonite

Rhodonite (Mn,Fe,Mg,Ca)SiO3