Sedimentary (Secondary Mineral Formation)

Flint

Chert (a form of cryptocrystalline quartz, chemical formula SiO₂)

Amygdaloidal Basalt with Epidote

Vesicular Basalt with secondary Epidote/Quartz mineral infill

Riverstone Quartzite (Water-worn Siltstone/Quartzite)

Metamorphosed Quartz-rich Arenite (SiO2)

Basalt with Quartz Veining

Amygdaloidal Basalt (predominately SiO2 and (Na,Ca)(Si,Al)4O8)

Quartzite with Iron Inclusions

Quartzite (primarily SiO2 with Fe2O3 impurities)

Quartz Vein with Iron Staining

Silicon Dioxide (SiO2) with limonite/hematite staining

Rough Diamond

Diamond (pure Carbon, C)

Basalt with Quartz Vein

Basalt (SiO2 vein inclusion)

Carnelian Agate

Silicon Dioxide with Hematite impurities (SiO2 + Fe2O3)

Sandstone (Muddy/Silty Variety)

Arenite with high silt/clay content (clastic sedimentary rock)

Man-made Slag (Industrial Byproduct)

Anthropogenic Glassy Residue

Gold Nugget

Native Gold (Au)

Chert (often called Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Carnelian

Carnelian (a variety of Chalcedony, which is a microcrystalline quartz, SiO2)

Chert (Jasper/Agate variety)

Microcrystalline Quartz (SiO2)

Carnelian Agate

Silicon Dioxide (SiO2) with iron oxide impurities

Amethyst (Quartz)

Silicon Dioxide with Iron impurities (SiO2)

Chrysocolla

Chrysocolla (Cu2-xAlx(H2-xSi2O5)(OH)4·nH2O)

Gold Nugget

Native Gold (Au)

Gold Nugget

Native Gold (Au)

Mixed Gemstone Bracelet

Mixed natural minerals and rocks (e.g., Rhodonite, Malachite, Sodalite, Rose Quartz, Black Tourmaline, Quartz/Chalcedony variants)

Turquoise

Hydrous phosphate of copper and aluminum (CuAl6(PO4)4(OH)8·4H2O)

Agate

Silicon Dioxide (SiO2)

Ferruginous Quartz (Iron-stained Quartz)

Silicon Dioxide (SiO2) with Hematite/Limonite impurities

Malachite

Copper carbonate hydroxide Cu2CO3(OH)2

Turquoise (Blue Howlite / Magnesite imitation)

CuAl6(PO4)4(OH)8·4H2O (for natural Turquoise); Ca2B5SiO9(OH)5 (for Howlite)

Prasiolite

Silicon Dioxide (SiO2) with iron impurities

Basalt (Vesicular)

Basalt (Mafic Extrusive Igneous Rock)

Calcite

Calcite (CaCO 3)

Milky Quartz

Silicon Dioxide (SiO2)

Ammolite

Biogenic gemstone (Aragonite, CaCO3)

White Quartz Pebble (Milky Quartz)

Silicon Dioxide (SiO2)

Black Sapphire (Basaltic Blue Sapphire)

Corundum (Al2O3)

Clear Quartz (beads in a bracelet)

Quartz (SiO2)

Moss Agate

Chalcedony (Silicon Dioxide / SiO2)

Moss Agate

Silicon Dioxide with inclusions (SiO2)

Azurite

Azurite (Cu3(CO3)2(OH)2)

Malachite

Copper carbonate hydroxide [Cu2CO3(OH)2]

Chrysocolla

Chrysocolla (Cu,Al)2H2Si2O5(OH)4·nH2O

Banded Gneiss

Gneiss (Metamorphic high-grade rock)

Amethyst

Amethyst (Varietal of Quartz), SiO2 (Silicon Dioxide)

Basalt with Quartz/Calcite Veins

Amygdaloidal Basalt (SiO2 or CaCO3 inclusions)