Organic Gemstone (Not A Rock)

Sandstone

Arenite (primarily SiO2)

Pink Granite

Phaneritic Felsic Intrusive Igneous Rock

Shale

Shale (composition varies: primarily clay minerals and quartz)

Sandstone (with potential Arkose/Lithic characteristics)

Arenite (Sedimentary rock composed of sand-sized grains)

Sandstone or Mudstone with Iron Staining

Ferruginous Sandstone/Mudstone

Rhodonite

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

Chert (specifically Jasper/Flint pebble)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Sandstone (lithic wacke)

Arenite / Lithic Wacke (mostly SiO2 with rock fragments)

Gneiss

Gneiss (High-grade regional metamorphic rock)

Common Opal

Hydrated amorphous form of silica (SiO2·nH2O)

Lapis Lazuli

Lazurite-rich metamorphic rock; (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2

Chert (Jasper/Flint variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (specifically Flint or Gray Chert)

Silicon Dioxide (SiO2)

Chert (variations include Flint/Jasper)

Chert (SiO2)

Chert (Yellow Jasper variant)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Dyed Quartzite

Metamorphosed Quartz (SiO2) with synthetic pigment

Basalt (River Pebble)

Basalt (dominated by Plagioclase Feldspar and Pyroxene)

Granite

Granite (Felsic Plutonic Rock)

Quartzite

Quartzite (SiO2)

Amethyst

Silicon Dioxide (SiO2) with trace Iron (Fe3+)

White Moonstone (Scolicite or White Feldspar var. )

Lattice-structure Silicate (KAlSi3O8)

Gold Placer (Gold Flakes and Nuggets)

Native Gold (Au)

Amethyst (Tumbled)

Silicon Dioxide (SiO2 with iron impurities)

Bauxite (Aluminum Ore)

Hydrated aluminum oxides, primarily Al(OH)3, AlO(OH)

Smoky Quartz

Smoky Quartz (Silicon Dioxide, SiO2)

Pyrite

Iron Sulfide (FeS2)

Blue Calcite

Calcium Carbonate (CaCO3)

Dyed Agate (Tumbled)

Silicon Dioxide (SiO2) - stained microcrystalline quartz

Gold

Native Gold (Au)

Quartzite

Quartzite (SiO2)

Sandstone

Clastic Sedimentary Rock (primarily Quartz, SiO2)

Carnelian Agate

Silicon Dioxide (SiO2) - variety of Chalcedony

Crushed Limestone Aggregate

Limestone (Calcium Carbonate, CaCO3)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Basalt

Extrusive mafic igneous rock

Quartzite

Quartzite (primarily SiO2)

Quartzite

Quartzite (primarily SiO2)

Chert (Iron-stained)

Chert (Microcrystalline and Cryptocrystalline Quartz, SiO2)

Dendritic Opal

Dendritic Common Opal (SiO2·nH2O with Manganese oxide inclusions)

Slate

Foliated Metamorphic Rock

Quartzite

Quartzite (primarily SiO2)