Anthropogenic Material (Man Made Rock)

Petrified Wood

Silicified Wood (primarily SiO2)

Chert (variations include Flint or Jasper)

Chert (chemical sedimentary rock), Quartz (SiO2)

Petrified Wood

Silicified Wood (SiO2)

Pyrite in Gossan

Iron Sulfide (FeS2) in Ferruginous Rock

Quartzite (Yellow/Tan)

Metamorphic Rock composed of Quartz (SiO₂)

Chert (Quartz Variety)

Silicon Dioxide (SiO2)

Ironstone (likely Limonite or Goethite)

Ferruginous sedimentary rock (FeO(OH)·nH2O)

Quartzite

Quartzite (composed primarily of Quartz, SiO2)

Quartzite

Metamorphosed Sandstone (SiO2)

Shale (possibly)

Shale (fine-grained clastic sedimentary rock)

Quartz

Silicon Dioxide (SiO2)

Granite

Granite (Felsic intrusive igneous rock)

Granite

Granite (Phaneritic Quartz-Feldspar Plutonic Rock)

Red Sandstone

Clastic Terrigenous Sedimentary Rock (primarily SiO2 with Fe2O3 coating)

Petrified Wood

Silicified wood (Quartz/Chalcedony/Opal)

Fulgurite

Fulgurite (Lechatelierite), amorphous SiO2

Variscite (or potentially a turquoise/variscite matrix cabochon, or an impression jasper)

AlPO4·2H2O (Variscite) or related phosphate/silicate material depending on exact composition

Chert (varietal: Jasper or Flint)

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Granite (Weathered)

Phaneritic Plutonic Rock (primarily Quartz, Feldspar, and Mica)

Petrified Wood

Silicified Wood (primarily SiO2 - Silicon Dioxide / Chalcedony)

Diorite (Salt and Pepper Rock)

Diorite

Diorite (Salt and Pepper Rock)

Phaneritic plutonic igneous rock (sodium-rich plagioclase feldspar and hornblende)

Serpentinite

Serpentinite (Mg, Fe, Ni, Al, Zn, Mn)2-3(Si, Al, Fe)2O5(OH)4

Pyrite (on host rock)

Iron Sulfide (FeS2)

Pumice

Pumice (volcanic glass with vesicular texture)

Limonite (Iron Ore/Sandstone mixture)

Limonite (FeO(OH)·nH2O) often mixed with Goethite and sedimentary matrix

Dendritic Agate (or Dendritic Opal)

SiO2 (for Agate), SiO2·nH2O (for Opal)

Nuummite

Nuummite (Orthorhombic amphiboles: Anthophyllite and Gedrite)

Laterite

Laterite (no specific mineral formula as it's a rock type)

Quartz

Quartz (SiO2, Silicon Dioxide)

Granite (Weathered River Rock)

Plutonic Igneous Rock (primarily Quartz, Feldspar, and Mica)

Coquina / Fossiliferous Limestone

Calcite-rich Bioclastic Sedimentary Rock (CaCO3)

Mica Schist

Mica Schist (primarily Muscovite or Biotite sheet silicates)

Greenstone (Greenschist)

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

Petrified Wood

Silicified Wood (SiO2)

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2 with iron oxide inclusions)

Sandstone

Arenite

Shale

Shale (clastic sedimentary rock)

Chert (Field Stone)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Pink Granite

Phaneritic plutonic rock (dominated by Alkali Feldspar)

Conglomerate with Fossilized Shark Teeth

Clastic sedimentary rock (Conglomerate) containing Elasmobranchii remains

Banded Calcite (often sold as 'Mexican Onyx')

Calcite (Calcium Carbonate, CaCO3)