Not A Natural Rock

Natural Pearl

Calcium carbonate (primarily Aragonite and Conchiolin), CaCO3

Quartz Pebble

Silicon Dioxide (SiO2)

Sandstone (Arkosic / Calcareous)

Arenite (primarily SiO2 with CaCO3/clay matrix)

Banded Sedimentary Rock (Wishbone Stone / Banded Quartzite or Limestone)

Silicified limestone or banded sedimentary rock with mineral veins

Granite Pebble

Granite

Shale

Argillaceous sedimentary rock

Sandstone

Sedimentary rock composed mainly of sand-sized minerals or rock grains

Dragon Vein Agate (Dyed)

SiO2

Amethyst (likely synthetic or treated)

Purple quartz, SiO₂; color caused mainly by trace iron and irradiation

Hag Stone

Perforated Sedimentary Rock (typically Flint, Chert, or Limestone)

Fossiliferous Limestone with Crinoid Stem

Sedimentary Rock with Echinodermata fossil fragment

Weathered conglomeratic rock, likely iron-stained sandstone

Probable ferruginous, clast-bearing sandstone; exact identification requires examination of a fresh surface

Sandstone

Sedimentary Rock (Quartz Sandstone)

Sandstone

Arenite

Sandstone

Clastic sedimentary rock

Sandstone

Sedimentary Clastic Rock

Sandstone

Sedimentary Clastic Rock

Sandstone

Sedimentary Clastic Rock

Quartzite (Engineered Stone)

Silicon Dioxide (SiO2) based synthetic composite

Natural turquoise

Turquoise — hydrated copper aluminum phosphate, CuAl₆(PO₄)₄(OH)₈·4H₂O

Quartz Breccia

Brecciated Quartz

Clear quartz sphere or polished quartz cabochon (tentative)

Quartz, silicon dioxide (SiO₂); appearance may also be consistent with ordinary glass, which cannot be ruled out from the image alone

Pink Dyed Agate Geode Slice

Silicon Dioxide (SiO2) with artificial pigment

Iron Ore (Limonite and Hematite)

Goethite/Limonite (FeO(OH)·nH2O) and Hematite (Fe2O3)

Granite

Plutonic Igneous Rock

Granite Cobble

Intrusive Igneous Rock

Red Sandstone

Clastic Sedimentary Rock

Tumbled purple stone, likely amethyst

Amethyst, violet quartz (SiO₂); identification from the image is tentative

Granite

Intrusive Igneous Rock

Vesicular Basalt (Lava Rock)

Basalt

Druzy Quartz on Matrix

Silicon Dioxide (SiO2) on host rock

Opalite (likely man-made glass)

Opalite; amorphous silica glass, not a natural mineral

Quartz Pebble (Tumbled / River Pebble)

Silicon Dioxide (SiO2)

Sandstone

Sedimentary Rock (Quartz arenite)

Sandstone

Clastic sedimentary rock composed mainly of quartz and feldspar

Quartz Pebble

Silicon Dioxide (SiO2)

Limonite (Iron Ore)

Hydrous ferric oxides (FeO(OH)·nH2O)

Rounded brown pebble, likely quartz-rich river stone

Indeterminate lithic pebble; possibly iron-stained quartzite or chert

Sandstone

Clastic sedimentary rock (Quartz arenite)

Agate (Carnelian type)

Silicon Dioxide (SiO2)

Sandstone Pebble

Ferruginous Sandstone (SiO2 with Fe2O3)

Pumice

Pumice (felsic volcanic rock)