Organic Gemstone (Not A Rock Or Mineral)

Schist

N/A (a rock type, not a mineral formula)

Granite

Granite (a common igneous rock)

Greenschist

Greenschist (chlorite-epidote schist)

Pink Granite

Phaneritic Felsic Intrusive Igneous Rock

River Rock (Greywacke/Sandstone)

Lithic Wacke

Quartz

Silicon Dioxide (SiO₂)

Orthoclase Feldspar

Orthoclase (KAlSi3O8)

Limonite (Iron Ore)

FeO(OH)·nH2O (Hydrated iron(III) oxide-hydroxide mixture)

Gneiss (specifically Granitic Gneiss)

Gneiss (composed primarily of Quartz, Feldspar, and Biotite/Amphibole)

Gossan with Copper Carbonate (Chrysocolla/Malachite)

Ferruginous Oxide (Gossan) with Cu2CO3(OH)2 (Malachite) or (Cu,Al)2H2Si2O5(OH)4 (Chrysocolla)

Amazonite

Amazonite (KAlSi3O8 - Microcline)

Chert (Agatized Chert)

Microcrystalline Quartz (SiO2)

Coquina / Limonite-stained Limestone

Sedimentary Limestone with Iron Oxyhydroxide (FeO(OH)·nH2O)

Clear Quartz (or Rock Crystal)

Quartz (SiO₂)

Moonstone

Orthoclase Feldspar ((K,Na)AlSi3O8)

Druzy Quartz on Sandstone

Silicon Dioxide (SiO2) with Quartz crystals

Moonstone (Feldspar)

Orthoclase (KAlSi3O8) or Albite (NaAlSi3O8)

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Amethyst (Druzy Quartz)

Amethyst (Silicon Dioxide - SiO2 with iron impurities)

Amygdaloidal Basalt

Amygdaloidal Basalt with Secondary Infilling (e.g., Agate, Quartz, or Zeolite)

Septarian Nodule (Thunder Egg)

Septarian Concretion (CaCO3 + CaMg(CO3)2 + SiO2)

Petrified Wood

Silicified Wood (SiO2 - primarily Quartz/Chalcedony/Opal)

Sandstone (Greywacke/Siltstone variant)

Arenite / Wacke (SiO2 with diverse mineral inclusions)

Labradorite (likely Black Labradorite or Larvikite)

Labradorite (Na,Ca)(Al,Si)4O8. If a rock, it is typically anorthosite, gabbro, or norite, or a variety of syenite called Larvikite if it is specifically from Larvik, Norway.

Turquoise

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

Amazonite

K(AlSi3O8), Microcline (potassium feldspar)

Clear Quartz

Silicon Dioxide (SiO2)

Lapis Lazuli (polished cabochon/sphere)

Na8[Al6Si6O24]Sn with accessory minerals (Pyrite, Calcite)

Amethyst (Quartz)

Silicon Dioxide (SiO2)

Petrified Wood (Silicified Wood)

Silicified Wood (primarily Chalcedony/Quartz, SiO2)

Petrified Wood

Silicified Wood (SiO2 - Silicon Dioxide)

Sandstone with Iron Concretion

Arenite with Limonite/Goethite Concretion

Green Aventurine

Silicon dioxide with Fuscite inclusions (SiO2 + K(Al,Cr)2AlSi3O10(OH)2)

Coal (specifically Bituminous or Anthracite)

Organic sedimentary rock; primarily Carbon (C) with varying H, S, O, N

Stardust (Micrometeorite)

Chondrite / Micrometeorite (Extraterrestrial Silicate)

Smoky Quartz

Silicon Dioxide (SiO2)

Garnet (Almandine or Spessartine likely)

Garnet Group Minerals (e.g., Almandine Fe3Al2(SiO4)3, Pyrope Mg3Al2(SiO4)3, Spessartine Mn3Al2(SiO4)3)

Quartz (likely milky/rose quartz variety)

Quartz (SiO2 - Silicon Dioxide)

Sandstone (likely Ferruginous)

Arenite (primarily SiO2 with Fe2O3 staining)

Moonstone (Orthoclase Feldspar)

(K,Na)AlSi3O8

Sandstone

Arenite (SiO2 primarily)