Not A Natural Rock (Man Made Composite)

Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Quartzite

Quartzite (composed primarily of Quartz, SiO2)

Opal

Hydrated Amorphous Silica (SiO2·nH2O)

Likely weathered basalt or mafic volcanic rock

Basalt; chiefly plagioclase feldspar, pyroxene, and commonly olivine or iron oxides

Ferruginous Conglomerate

Ferruginous Conglomerate (Clastic Sedimentary Rock)

Turquoise

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

Travertine

Travertine (CaCO3 - Calcium Carbonate)

Turquoise

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

Quartz (Rock Crystal) with minor impurities

Quartz (SiO2)

Granite

Granite (a common rock name, not a single mineral species, composed primarily of quartz, feldspar, and mica/amphibole)

Chert Nodule (with Ironstone Cortex)

Microcrystalline Silica (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Granite

Phaneritic Igneous Rock (composed primarily of Quartz, Alkali Feldspar, and Plagioclase)

White Opal

Hydrated Amorphous Silica (SiO2·nH2O)

Slate

Foliated Metamorphic Rock (primarily composed of quartz, illite, chlorite, and micas)

Carnelian Agate

Silicon Dioxide (SiO2) with Iron Oxide impurities

White granite

Granite, chiefly quartz–alkali feldspar–plagioclase with biotite/hornblende

Native American Hammerstone / Pitted Stone

Modified lithic artifact (often quartzite, basalt, or granite)

Quartzite Pebble (with mineral veining)

Metamorphic Quartzite (SiO2)

Hag Stone

Sandstone or Limestone with Solution Holes (Bioturbation/Erosion)

Yellow Quartz Pebble

Silicon Dioxide (SiO2)

Turquoise

CuAl6(PO4)4(OH)8·4H2O

Gossan (Iron Hat)

Goethite-Hematite rich weathered rock (Fe-hydroxides)

Wishing Stone with Quartz Vein

Quartz-veined sedimentary pebble

Black Onyx

Silicon Dioxide (SiO2) with cryptocrystalline structure

Weathered iron-rich rock, likely limonite-bearing sandstone or laterite

Limonite/goethite-rich ferruginous rock; composition commonly FeO(OH)·nH₂O with quartz and clay minerals

Shale with Limonite/Hematite Staining

Argillaceous sedimentary rock with Iron Oxides (FeO(OH)·nH2O / Fe2O3)

Tumbled-looking granite pebble

Granite, chiefly quartz–feldspar with biotite/amphibole

Orange chromium diopside (likely tumbled)

Diopside, CaMgSi₂O₆; orange color may reflect iron-rich composition or surface treatment/inclusion

Quartzite

Quartzite (primarily SiO2)

Blue Sapphire

Corundum (Al2O3)

Herkimer Diamond

Quartz (Silicon Dioxide, SiO2)

River Cobble (likely Sandstone or Siltstone type)

Sandstone or Siltstone (common rock types that form river cobbles)

Granite

Phaneritic high-silica plutonic rock (composed primarily of Quartz, Feldspar, and Mica)

Weathered iron-rich sandstone or ferruginous siltstone

Clastic sedimentary rock, likely quartz-rich sandstone cemented by iron oxides (Fe₂O₃/Fe₃O₄)

Quartzite

Quartzite (primarily SiO2)

Ironstone (Limonitic Shale)

Ferruginous Siltstone / Goethite-rich Sedimentary Rock

Carnelian (a variety of Chalcedony)

Silicon Dioxide (SiO2) with iron oxide impurities

Schist (Kyanite Schist)

Kyanite-Mica Schist (primarily Al2SiO5, KAl2(AlSi3O10)(OH)2, and SiO2)

Basalt Pebble with Quartz Inclusion

Basalt (SiO2 with Fe, Mg silicates) with Quartz (SiO2)

Turquoise

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

Polished ocean jasper (orbicular jasper), probable

Microcrystalline quartz (SiO₂), chiefly chalcedony with iron-oxide and other mineral inclusions