Metamorphic Or Igneous (Context Dependent)

Pyrite on Quartz

Iron Sulfide (FeS2) on Silicon Dioxide (SiO2)

Quartz crystal with Pyrite inclusions

Silicon Dioxide (SiO2) with Iron Sulfide (FeS2)

Milky Quartz

Silicon Dioxide (SiO2)

Milky Quartz with Chlorite/Moss Infusions

Silicon Dioxide (SiO2)

Fossil bivalve shell

Fossilized or partially mineralized bivalve; exact genus cannot be determined from the image

Milky Quartz with Iron Staining

Silicon Dioxide (SiO2)

Gold Placer (Gold Flakes and Nuggets)

Native Gold (Au)

Geode or Concretion

Silica-rich Concretion or Unopened Geode (SiO2)

Quartz Pebble

Crystalline Silica (SiO2)

Parti Sapphire

Corundum (Al2O3)

Quartz Vein in Host Rock

Silicon Dioxide (SiO2)

Granite cobble

Granite (composed primarily of Quartz, Feldspar, and Mica)

Quartz / Calcite Vein Rock

Silicon Dioxide (SiO2) or Calcium Carbonate (CaCO3)

Milky Quartz with inclusions

Silicon Dioxide (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Sandstone

Arenite (primarily Quartz Sandstone)

Sodium Polyacrylate (Superabsorbent Polymer)

Sodium Polyacrylate [-CH2-CH(COONa)-]n

Tumbled chalcedony (likely gray/brown agate)

Microcrystalline quartz, SiO₂ (chalcedony; possible agate variety)

Nickel coin (U.S. currency)

Cupronickel (75% Copper, 25% Nickel alloy)

Milky Quartz (Quartz Vein)

Silicon Dioxide (SiO2)

Milky Quartz (Common Quartz)

Quartz (Silicon Dioxide, SiO2)

Jasper

Agate/Jasper (Microcrystalline Quartz, SiO2)

Chert (Arrowhead/Projectile Point)

Microcrystalline Quartz (SiO2)

Blue Quartz (or Blue Aventurine)

Silicon Dioxide (SiO2) with inclusions (typically Crocidolite or Dumortierite)

Granite

Granite (a common type of Felsic Intrusive Igneous Rock)

Milky Quartz Vein in Host Rock

Silicon Dioxide (SiO2)

Glauconitic Sandstone (or Greenstone)

Glauconitic Sandstone with Quartz

Fossilized bivalve or brachiopod shell

Indeterminate calcitic shell fossil; likely Bivalvia or Brachiopoda

Kidney Stone

Calcium Oxalate (CaC2O4), Uric Acid, or Struvite

Basalt (Crushed Stone)

Basalt (Mafic Extrusive Igneous Rock)

Emerald

Beryl (Be3Al2Si6O18 with Chromium/Vanadium impurities)

Blue Sapphire

Corundum (Al2O3)

Rough Emerald

Beryl (Be3Al2Si6O18 with Chromium/Vanadium impurities)

Fluorite

Fluorite (Calcium Fluoride, CaF2)

Quartz (Iron-stained)

Silicon Dioxide (SiO2) with Iron Oxide impurities

Sandstone (Water-worn Cobble)

Arenite (variable composition, primarily SiO2)

Weathered iron-rich rock, possibly laterite or limonite-bearing stone

Hydrated iron oxides/hydroxides, chiefly limonite-goethite mixture; exact identification requires testing

Quartz Vein in Host Rock

Silicon Dioxide (SiO2)

Sandstone

Sandstone (Quartzose/Feldspathic Sandstone)

Seashell (Cone Snail Shell)

Conus sp. (Calcium Carbonate, CaCO3)

Sandstone (likely Ferruginous)

Sandstone (SiO2 with iron oxides)

Quartzite

Quartzite (primarily SiO2)