Sedimentary Rock (Specifically A Clastic Sedimentary Rock Formed Into A Cobble)

Chert (Chalcedony/Agate)

Microcrystalline Quartz (SiO2)

Sandstone Concretion

Ferruginous Sandstone Concretion (Primarily SiO2 with Iron Oxide cement)

Moss Agate

Silicon Dioxide (SiO2) with inclusions of Manganese or Iron oxides

Chert (White Flint)

Microcrystalline Quartz (SiO2)

Turquoise (Green variety)

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

Geode with Quartz and Chalcedony

Silicon Dioxide (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Yellow Jasper

Silicon Dioxide (SiO2) with iron oxide impurities

Mica Schist

Foliated Metamorphic Rock (Schist)

Quartz Druse (on Chalcedony/Agate base)

Silicon Dioxide (SiO2)

Coal

Bituminous or Anthracite coal (carbon-rich sedimentary rock)

Hag Stone

Porous sedimentary rock (typically Flint, Chert, or Sandstone) with naturally occurring holes

Red Jasper with Quartz

Silicon Dioxide (SiO2) with Hematite inclusions

Pink Granite

Granite (Phaneritic Felsic Igneous Rock)

Chert (Jasper focus)

Silicon dioxide (SiO2) - Microcrystalline Quartz

Carnelian Agate

Silicon Dioxide (SiO2) - Variety: Chalcedony

Fossiliferous Chert (with Brachiopod or Mollusk fragments)

Silicon dioxide (SiO2) with Calcium Carbonate (CaCO3) inclusions

Chert (Jasper)

Microcrystalline Quartz (SiO2)

Banded Gneiss with Quartz Vein

Foliated Metamorphic Rock (Gneiss)

Quartz (Milky/Common)

Quartz (Silicon Dioxide, SiO2)

Granite (specifically Pink or Alkali Feldspar Granite)

Felsic Plutonic Rock (primarily SiO2 with KAlSi3O8)

Granite (with Orthoclase and Quartz)

Phaneritic Felsic Igneous Rock (KAlSi3O8 + SiO2)

Anthracite Coal

Anthracite (Carbon-rich metamorphic sedimentary rock)

Gneiss

Gneiss (High-grade Metamorphic Rock)

Chert (variations include Flint or Jasper)

Chert (chemical sedimentary rock), Quartz (SiO2)

Stromatolite

Biogenic Sedimentary Rock (Lithified microbial mat)

Orange Calcite

Calcium Carbonate (CaCO3)

Quartz Geode

Silicon Dioxide (SiO2) within a secondary sedimentary structure

Bituminous Coal

Organic-rich sedimentary rock (Complex hydrocarbons)

Fossiliferous Limestone

Calcite (CaCO3) Rich Bio-sedimentary Rock

Ironstone (Limonitic Shale)

Ferruginous Siltstone / Goethite-rich Sedimentary Rock

Granite Gneiss

Felsic Gneiss

Red Jasper (possibly Chert/Argillite)

Jasper (SiO2) with iron oxide inclusions

Dendrite (Manganese Oxide Dendrites)

Psilomelane or Pyrolusite on Matrix (typically MnO2)

Sandstone

Arenite (SiO2 based)

Banded Agate (Orca Agate)

Silicon Dioxide (SiO2) - Chalcedony variety

Schist (specifically Chlorite/Greenschist)

Chlorite Schist

Red Jasper

Silicon Dioxide with Iron Oxide (SiO2)

Blue Kyanite

Kyanite (Al2SiO5)

Selenite

Gypsum (Calcium Sulfate Dihydrate) - CaSO4·2H2O

Chert (Nodule)

Silicon Dioxide (SiO2)

Bauxite

Bauxite (Al(OH)3, AlO(OH))