Organic Gemstone (Not A Rock Or Mineral In The Traditional Sense, But Bio Mineralized Material)

Sandstone Cobble

Arenite (Secondary classification based on grain size)

Sandstone (Ferruginous)

Arenite (Fe2O3 rich)

Limestone

Calcium Carbonate (CaCO3)

Sandstone (Ferruginous)

Arenite with Iron Oxide cement

Granodiorite

Granodiorite (Na,Ca)(Si,Al)4O8

Chrysocolla (with Quartz and Azurite)

Hydrated copper phyllosilicate mineral [Cu2-xAlx(H2-xSi2O5)(OH)4·n(H2O)]

Sandstone

Arenite

Granite Pebble

Granite (composed primarily of Quartz, Feldspar, and Mica)

Limonite with Opal infusion

FeO(OH)·nH2O (Limonite) / SiO2·nH2O (Opal)

Chert Nodule (Fossiliferous Chert)

Microcrystalline Quartz (SiO2)

Granite Cobble

Plutonic Igneous Rock (Granitic)

Red Sandstone

Clastic sedimentary rock (primarily SiO2 with Fe2O3 iron oxide staining)

Sandstone (Ferruginous)

Arenite (with iron oxide cement, Fe2O3)

Sandstone

Arenite (composed primarily of SiO2)

Turquoise and Hematite

Turquoise (CuAl6(PO4)4(OH)8·4H2O) and Hematite (Fe2O3)

Sandstone (with manganese staining)

Clastic sedimentary rock (primarily SiO2)

Chert (variations include Flint/Jasper)

Cryptocrystalline Quartz (SiO2)

Dragon Stone

Ohko Stone (Argillaceous sedimentary rock)

Sandstone

Clastic Sedimentary Rock (composed of SiO2 grains)

Green Moonstone (Garnierite)

Nickel-bearing Magnesium Silicate (often a mix of Serpentine and Talc/Chlorite groups)

Sandstone (Quartzose Sandstone)

Clastic Sedimentary Rock (Lithic arenite / Quartz arenite)

Peridot

Olivine ((Mg,Fe)2SiO4)

Quartz (Gravel fragment)

Quartz (Silicon Dioxide, SiO2)

Sandstone

Arenite (SiO2 based with mineral cement)

Sandstone

Arenite (composed primarily of SiO2)

Petrified Wood (Silicified Wood)

Silicified Wood (primarily Chalcedony/Quartz, SiO2)

Sandstone (Ferruginous)

Arenite (with high iron oxide content)

Rough Diamond

Diamond (Native Carbon, C)

Basalt

Basalt (composition of plagioclase feldspar and pyroxene)

Moss Agate

Chalcedony (SiO2) with dendritic inclusions of Manganese or Iron oxide

Sandstone (Ferruginous)

Arenite (composed primarily of SiO2 with Fe2O3 staining)

Ferruginous Quartz Cobble

Silicon Dioxide (SiO2) with Iron Oxide inclusions

Drupa Quartz (Sparkly Drusy Quartz on Matrix)

Crystalline Silicon Dioxide (SiO2) on host rock

Granite

Phaneritic Felsic Igneous Rock (Granite)

Note regarding image quality

Quartz (Milky or Smoky Quartz)

Silicon Dioxide (SiO2)

Peridot (Olivine)

Olivine (Magnesium Iron Silicate - (Mg, Fe)2SiO4)

Quartz (Milky/Common)

Silicon Dioxide (SiO2)

Sodalite

Sodalite (Na8(Al6Si6O24)Cl2)

Sandstone

Arenite (composed primarily of SiO2)

Jasper River Stone

Silicon Dioxide with Iron Oxide impurities (SiO2 + Fe2O3)

Amethyst

Amethyst (Silicon Dioxide - SiO2 with iron impurities)