Sedimentary (Secondary Classification For A Weathered Mineral Specimen)

Fossil / Permineralized Bone

Tyrannosaurus rex fossil (Hydroxylapatite replaced by various minerals)

Gneiss Pebble

Gneiss (High-grade metamorphic rock)

Quartz (Citrine or Iron-Stained)

Silicon Dioxide (SiO2)

Chert Nodule (Flint)

Chert (Cryptocrystalline Silica - SiO2)

Tree Agate

Dendritic Chalcedony (SiO2)

River Rock (Basalt/Greywacke)

Aphanitic Basalt or Lithic Sandstone (Greywacke)

Fossilized Shark Tooth (Sand Tiger)

Carcharias taurus (fossil specimen)

Amygdaloidal Basalt with Quartz Infill

Basalt (SiO2 for the quartz inclusion)

Sandstone (Greywacke)

Arenite/Greywacke (SiO2 major)

Turquoise

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

Quartz (chalcedony variety) or Limestone with Quartz Veins

SiO2 (for Quartz/Chalcedony); CaCO3 (for Limestone)

Chalcedony on Matrix

Silicon Dioxide (SiO2)

Blue Apatite

Apatite-(CaF), Ca5(PO4)3F

Angelite

Anhydrite (CaSO4)

Chalcedony (Agate)

Chalcedony (Cryptocrystalline Quartz, SiO2)

Pyrite in Matrix (Fool's Gold)

Iron Disulfide (FeS2)

Bauxite

Bauxite (mixture of Gibbiste Al(OH)3, Boehmite ̳-AlO(OH), and Diaspore ́-AlO(OH))

Turquoise

Hydrated phosphate of copper and aluminium, CuAl6(PO4)4(OH)8·4H2O

Sandstone (Ferruginous)

Clastic Sedimentary Rock (Litharenite)

Sandstone (likely Arkosic)

Clastic Sedimentary Rock (primarily SiO2 with Feldspar)

Quartzite river stone

Quartzite (SiO2)

Chalcedony (Common Agate)

Silicon Dioxide (SiO2)

Jasper

Jasper (Silicon Dioxide, SiO2)

Malachite Coating on Host Rock

Malachite [Cu2CO3(OH)2]

Septarian (Dragon Stone)

Septarian concretion (Calcite, Aragonite, and Limestone)

Jasper

Silicon dioxide (SiO2)

Siltstone or Limestone Beach Pebble

Siltstone / Micritic Limestone

River Cobble (likely Quartzite or Limestone)

SiO2 (Quartzite dominant) or CaCO3 (Limestone dominant)

Basalt (Water-worn Pebble)

Basalt (Mafic Extrusive Igneous Rock)

Flint

Silicon Dioxide (SiO2) - variety of Chert

Sandstone (Ferruginous)

Arenite (composed primarily of SiO2 with Fe2O3 staining)

Petrified Wood

Silicified Wood (SiO2)

Quartz

Silicon Dioxide (SiO2)

Sandstone (Quartz Sandstone)

Arenite (primarily SiO2)

Chalcedony (River Agate)

Silicon Dioxide (SiO2)

Quartz (Chalcedony)

Silicon Dioxide (SiO2)

Chalcedony (Agate/Carnelian type)

Silicon Dioxide (SiO2)

Chalcedony (Quartz Pebble)

Cryptocrystalline Quartz (SiO2)

Sandstone (Calcareous or Ferruginous)

Clastic sedimentary rock (SiO2 with CaCO3 or Fe2O3 cement)

Wonderstone (Liesegang Sandstone)

Silicified Sandstone with Liesegang Rings (SiO2 + FeO(OH))

Quartz / Quartzite

Quartz (Silicon Dioxide, SiO2)

Sandstone (with Iron Staining)

Clastic sedimentary rock (primarily SiO2 with Fe2O3 staining)