Synthetic (Not A Natural Rock)

Ironstone Nodule (Ironstone Concretion)

Siderite-rich Mudstone (FeCO3) or Limonite (FeO(OH)·nH2O)

Sandstone

Quartz Sandstone (predominantly)

Quartzite

Quartzite (SiO2)

Chert (Arrowhead variety)

Chert (SiO2)

Dalmatian Stone (often called Dalmatian Jasper)

Peralkaline Quartz-Feldspar Rock with Arfvedsonite (formerly believed to be Jasper)

Yellow Quartzite (River Pebble)

Quartzite (primarily SiO2)

Turquoise

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

Quartzite (or Milky Quartz pebble)

Quartzite (primarily Silicon Dioxide, SiO2)

Moss Agate

Silicon Dioxide with inclusions (SiO2 + impurities)

Amazonite

K(AlSi3O8) - Microcline variant

Bumblebee Jasper

Calcite with Arsenic and Manganese oxides (technically a volcanic rock)

Shungite

Shungite (Amorphous Carbon)

Yellow Jasper

Chalcedony (SiO2) with iron oxide inclusions

Banded Gneiss

Gneiss (High-grade regional metamorphic rock)

Yellow Jasper

Silicon Dioxide with Iron inclusions (SiO2)

Diamond

Diamond (pure Carbon, C)

Moss Agate / Carnelian Agate

Silicon Dioxide (SiO2) with iron and manganese inclusions

Black Tourmaline (Schorl)

Schorl (Sodium iron silicate hydroxide boron silicate); NaFe3Al6(BO3)3Si6O18(OH)4

Natural Pearl (appearing in a jewelry setting)

Calcium Carbonate (mostly Aragonite), CaCO3 with Conchiolin

Granite (Alkali-feldspar rich)

Phaneritic Felsic Igneous Rock (Major components: KAlSi3O8, SiO2)

Gneiss

Gneiss (High-grade regional metamorphic rock)

Blue Chalcedony

Silicon Dioxide (SiO2)

Bloodstone (also known as Heliotrope)

Silicon Dioxide (SiO2) - variety of Chalcedony

White Marble

Calcite-rich Metasomatized Carbonate (CaCO3)

Lapis Lazuli

Complex metamorphic rock consisting mainly of Lazurite (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2, Calcite, and Pyrite

Rainbow Fluorite

Fluorite (Calcium Fluoride, CaF2)

Quartzite Pebble

Quartzite (primarily SiO2)

Quartz (in a rock matrix)

Quartz (SiO2)

Amethyst

Silicon Dioxide (SiO2) with iron impurities

Amethyst (Pale/Lavender variety)

Silicon Dioxide (SiO2)

Yellow Jasper

Silicon Dioxide (SiO2) with Goethite or Iron Oxide inclusions

Turquoise

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

Engineered Quartz Stone

Agglomerated Quartz (SiO2 + Polymer Resin)

Amethyst

Silicon dioxide with iron impurities (SiO2)

Amethyst

Silicon dioxide (SiO2) containing traces of iron and manganese

Dalmatian Stone

Dalmatian Jasper / Feldspathic Igneous Rock

Diamond

Diamond (C)

Crinoid Stem Fossil

Class Crinoidea (Phylum Echinodermata), primarily Calcium Carbonate (CaCO3)

Amazonite

KAlSi3O8 (Potassium Aluminum Silicate) - a variety of Microcline Feldspar

Chert (Flint)

Chert (predominantly SiO₂ - silicon dioxide)

Pearl (with Peridot)

Calcium carbonate (CaCO3) + Conchiolin; Peridot: Magnesium iron silicate (Mg, Fe)2SiO4

Popcorn

Zea mays everta (P. Wilson) (Botanical name for the corn variety)