Mineral Based Human Made Alloy

Chert (River Pebble)

Chert (Microcrystalline Silicon Dioxide, SiO2)

Pearl and Garnet Glass

Calcium Carbonate (CaCO3) for pearl; Silicon Dioxide (SiO2) for glass

Quartz Geode

Silicon Dioxide (SiO2)

Limonite (Iron Ore)

FeO(OH)·nH2O

Limonite (Yellow Ochre)

Hydrated iron(III) oxide-hydroxide (FeO(OH)·nH2O)

Opalite Egg

Synthetic Glass (Simulated Opal)

Rainbow Hematite Ring

Iron(III) oxide (Fe2O3) with thin-film coating

Chert (variations include Flint/Jasper)

Chert (SiO2)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Amethyst and clear gemstone ring

Amethyst (purple quartz, SiO₂), likely set with colorless quartz or glass accents

Tree Agate

Chalcedony (SiO2)

Ironstone Concretion (Pot Stone)

Siderite or Limonite Concretion (FeCO3 or FeO(OH)·nH2O)

Banded sandstone pebble

Lithic or quartz-rich sandstone; exact composition requires testing

Chert / Flint

Cryptocrystalline quartz (SiO2)

Sandstone

Arenite (composed primarily of SiO2)

Chert (Jasper)

Cryptocrystalline Silica (SiO2)

Swirled Agate Bead

Silicon Dioxide (SiO2)

Natural Pearl (appearing in a jewelry setting)

Calcium Carbonate (mostly Aragonite), CaCO3 with Conchiolin

Rough Diamond

Diamond (pure Carbon, C)

Amethyst (Tumbled Cabinet Stone)

Silicon Dioxide (SiO2) with iron impurities

Diamond

Native Carbon (C)

Chert / Flint

Chert (Cryptocrystalline Quartz, SiO2)

Chert (Flint)

Silicon Dioxide (SiO2)

Chert (Jasper/Flint variant)

Silicon Dioxide (SiO2)

Chert (often called Flint)

Cryptocrystalline Quartz (SiO2)

Brown Chert (Jasper-like)

Silicon Dioxide (SiO2)

Tumbled jasper, likely red jasper

Microcrystalline quartz (SiO₂), chalcedony variety with iron-oxide impurities

Milky quartz (likely vein quartz)

Quartz, silicon dioxide (SiO₂)

Moldavite

Tektite (Impact Glass), ~80% SiO2 + Al2O3

Sandstone

Arenite (SiO2 composition dominant)

Chert (Flint)

Silicon Dioxide (SiO2)

Muscovite

Muscovite (KAl2(AlSi3O10)(OH)2)

Chert (River Pebble)

Microcrystalline Quartz (SiO2)

Sea Glass

Amorphous silicon dioxide (man-made glass weathered by nature)

Engineerged Quartz (Quartz Composite)

SiO2 (Silicon Dioxide) in a polymer resin matrix

Fossilized Coral (Petoskey Stone / Hexagonaria)

Hexagonaria percarinata / Rugosa coral (CaCO3)

Granite

Phaneritic Igneous Rock (primarily Quartz, Feldspar, and Mica)

Banded Slate or Siltstone with Quartz/Calcite Veins

Protolith-derived Siltstone or Slate (varies based on degree of metamorphism)

Granite

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

Quartz with Mica

SiO2 (Quartz) with Potassium aluminum silicate (Muscovite)

Limonite (Ironstone)

Goethite/Limonite (Hydrated iron(III) oxide-hydroxide)

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)