Mineral Like Byproduct

Chalcedony (Common Opal variant)

Silicon dioxide (SiO2) with varying levels of hydration

Amethyst (Tumbled)

Amethyst (Silicon Dioxide, SiO2 + Fe4+)

Olivine (Peridot)

Magnesium Iron Silicate (Mg, Fe)2SiO4

Blue Chalcedony

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Fossilized Bone Fragment

Permineralized Skeletal Element (Likely Vertebrate)

Moss Agate

Silicon Dioxide (SiO2) with Chlorite/Oxide inclusions

Jasper (Green Jasper/Chert)

Silicon Dioxide (SiO2)

Dendritic Agate

Silicon Dioxide with Manganese/Iron oxide inclusions (SiO2)

Quartz (Milky or Iron-Stained)

Silicon Dioxide (SiO2)

Potassium Feldspar (Orthoclase)

Orthoclase (KAlSi3O8)

Sandstone (specifically Lithic or Quartz Arenite)

Arenite (composed primarily of SiO2)

Magnetite (Lodestone variety)

Magnetite (Iron(II,III) oxide, Fe3O4)

Goethite (Iron Ore)

Goethite (FeO(OH))

Sandstone

Arenite (primarily SiO2)

Limonite (Iron Ore)

Hydrous ferric oxides (FeO(OH)·nH2O)

Amethyst (Tumbled Quarz)

Silicon Dioxide (SiO2) with iron impurities

Quartz / Clear Quartz

Silicon Dioxide (SiO2)

Quartz (Chert/Chalcedony Variety)

Silicon Dioxide (SiO2)

Sandstone (Ferruginous)

Arenite (with Iron Oxides)

Obsidian

Volcanic Glass (SiO2)

Lepidolite

Lepidolite (K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2)

Sandstone with Secondary Mineral Encrustation

Arenite with Silica/Calcite deposits (SiO2 or CaCO3)

Moss Agate

Silicon Dioxide with inclusions (SiO2)

Schist

Crystalline Schist (often containing Muscovite, Biotte, or Quartz)

Obsidian (specifically Rainbow or Silver Sheen Obsidian)

Volcanic Glass (predominantly SiO2)

Turquoise

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

Gneiss

Gneiss

Dyed Quartz (often sold as 'Blue Quartz' or 'Blue Agate')

Silicon Dioxide (SiO2) with artificial pigment

Sandstone (Ferruginous)

Arenite (with Iron Oxide)

Chert (often called Flint or Jasper)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Greenschist

Greenschist

Basalt with Epidote (Greenstone)

Epidote-bearing Metabasalt

Greenschist (Greenstone)

Greenschist (Metamorphic rock containing chlorite, actinolite, and epidote)

Lepidolite

K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2 (Lithium-bearing Phyllosilicate)

Milky Quartz with Iron Inclusions

Silicon Dioxide (SiO2)

Gneiss (specifically a weathered Amphibolite or Garnet Gneiss)

Gneiss (complex silicate composition)

Arfvedsonite (often mistakenly sold as Astrophyllite)

Arfvedsonite [Na3(Fe2+)4Fe3+Si8O22(OH)2]

Basalt with Amygdules

Amygdaloidal Basalt

Limonite Sandstone

Ferruginous Sandstone (Hydrated Iron Oxide)

Geode (Unbroken)

Silicon Dioxide (SiO2) usually as Microcrystalline Quartz or Chalcedony

Quartz Geode

Silicon Dioxide (SiO2) in a concretionary structure

Orthoclase Feldspar

Orthoclase (KAlSi3O8)