Mineral Based Human Made Alloy

Yellow Chert (Chalcedony)

Microcrystalline Quartz (SiO2)

Chert (Jasper/Flint variety)

Microcrystalline quartz (SiO2)

Chert (often called Flint or River Stone)

Microcrystalline alpha-quartz (SiO2)

Polished blue spotted stone, likely K2 stone

K2 stone: granite containing blue azurite spots; quartz–feldspar–biotite matrix

Red Moss Agate (Jasper)

Silicon Dioxide (SiO2) with Iron Oxide inclusions

Rose Quartz

Silicon dioxide (SiO2) with traces of titanium, iron, or manganese

Sandstone Pebble

Arenite (SiO2 with minor mineral cements)

Kidney Stone

Nephrolithiasis (Calcium Oxalate, Hydroxyapatite, or Uric Acid)

Dendritic Agate

Silicon Dioxide (SiO2) with Manganese/Iron oxide inclusions

Chert (specifically Flint or Gray Chert)

Silicon Dioxide (Microcrystalline Quartz), SiO2

Vanadinite on Barite

Pb5(VO4)3Cl (Vanadinite) with BaSO4 (Barite)

Granite (with Beryl/Aquamarine)

Granite (Feldspar, Quartz, Mica, and Beryl Be3Al2Si6O18)

Standing Liberty Quarter (Silver Specimen)

Native Silver alloy (Ag with Cu traces)

Sandstone

Arenite (primarily Quartz-based)

Sandstone

Arenite (SiO2 based typically)

Sandstone

Arenite (SiO2 based typically)

Gold

Native gold (Au)

Limonite

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

Diabase (Greenstone)

Diabase (also known as Dolerite)

Bumblebee Jasper

Anhydrous Calcium Carbonate with Sulfur and Arsenic (Orpiment/Realgar)

Chert (Nodular or Massive Variety)

Cryptocrystalline Quartz (SiO2)

Brown Chert

Cryptocrystalline Silica (SiO2)

Limonite (Iron Ore/Sandstone mixture)

Limonite (FeO(OH)·nH2O) often mixed with Goethite and sedimentary matrix

Milky Quartz

Silicon Dioxide (SiO2)

Quartz

Silicon Dioxide (SiO2)

Granodiorite

Granodiorite

Citrine Quartz

Citrine (Silicon Dioxide, SiO2)

Tumbled orbicular jasper

Orbicular jasper; microcrystalline quartz (SiO₂) with iron oxides and feldspathic/chalcedony inclusions

Calcite crystal cluster

Calcite (calcium carbonate, CaCO₃)

Sandstone

Arenite (SiO2 based with various mineral cements)

Polished blue calcite sphere (tentative identification)

Calcite, CaCO₃; blue color generally results from trace impurities or inclusions

Sandstone (likely Calcareous or Quartz-rich)

Arenite (SiO2 based typically)

Sandstone (Ferruginous)

Arenite (SiO2 based with Fe2O3 banding)

Sandstone

Arenite (SiO2 based with various mineral cements)

Tumbled quartz-rich stone, possibly blue quartz or granite

Quartz (SiO₂), with probable feldspar and dark accessory minerals

Limestone Pebble

Sedimentary Calcium Carbonate (CaCO3)

Moss Agate

Silicon Dioxide (SiO2) with inclusions of manganese or iron oxides

Quartz vein material

Quartz (SiO₂), likely milky quartz with iron-oxide staining

Aura Quartz

Titanium/Titanium-Gold treated Silicon Dioxide (SiO2)

Pebble

Lithified clastic rock fragment / Quartz-rich pebble

Chert (Nodule)

Silicon dioxide (SiO2) - Cryptocrystalline Quartz

Beryl (Emerald Variety)

Beryllium aluminum silicate (Be3Al2(SiO3)6) with chromium/vanadium traces