Organic Gemstone (Not A Mineral)

Chlorastrolite (Greenstone)

Chlorastrolite (variety of Pumpellyite) - Ca2(Mg,Fe)Al2(SiO4)(Si2O7)(OH)2 · H2O

Blue Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2 with inclusions of asbestiform silicates)

Sunstone

Aventurine Feldspar (Plagioclase Feldspar with inclusions)

Red Beryl

Bixbite (Be3Al2Si6O18 with Mn3+ ions)

Citrine

Silicon Dioxide (SiO2) - Yellow Quartz variety

Amethyst with Marcasite accents

Amethyst (Silicon Dioxide SiO2) and Marcasite (Iron Sulfide FeS2)

Yellow Quartz (Citrine Quartz Pebble)

Silicon Dioxide (SiO2)

Peridot (Olivine)

Magnesium Iron Silicate (Mg,Fe)2SiO4

Amazonite

Amazonite (KAlSi3O8); a green variety of Microcline feldspar

Citrine

Citrine (Silicon Dioxide, SiO2)

Amethyst

SiO2 (Silicon Dioxide with iron impurities)

Amethyst

SiO2 (Silicon Dioxide) with Iron (Fe3+) impurities

Rough Citrine Quartz

Citrine (Silicon Dioxide, SiO2 with iron impurities)

Smoky Quartz

Smoky Quartz (Silicon Dioxide - SiO2)

Black Opal

Hydrated Amorphous Silica (SiO2·nH2O)

Red Jasper

Silicon dioxide (SiO2) with iron oxide (Fe2O3) inclusions

Quartz Geode

Silicon Dioxide (SiO2)

Petrified Wood

Silicified Wood (SiO2)

Smoky Quartz

Silicon Dioxide (SiO2)

Raw Corundum (Sapphire/Ruby variant)

Aluminum oxide (Al2O3)

Chert (varieties include Flint or Jasper)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Pearl (Imitation or Cultured)

Calcium Carbonate (Aragonite/Calcite) - CaCO3

Diamond (or Cubic Zirconia)

Carbon (C) or Zirconium Dioxide (ZrO2)

Chert (Flint Nodules)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Petrified Wood

Silicified wood (primarily Silicon Dioxide - SiO2)

Prehnite

Prehnite (Ca2Al2Si3O10(OH)2)

Dendritic Agate (or Dendritic Opal)

SiO2 (for Agate), SiO2·nH2O (for Opal)

Chrysocolla

Chrysocolla; (Cu,Al)2H2Si2O5(OH)4·nH2O

Quartz (Chatoyant or Milky variety)

Silicon Dioxide (SiO2)

Hypersthene

(Mg,Fe)SiO3 - Enstatite-Ferrosilite series

Yellow Chert (Jasper)

Microcrystalline Quartz (SiO2)

Chert (specifically Flint or Gray Chert)

Silicon Dioxide (Microcrystalline Quartz), SiO2

Peridot

Olivine ((Mg, Fe)2SiO4)

Ironstone Concretion (Ironstone Gourd)

Limonite/Goethite Concretion (FeOO(H))

Blue Apatite

Apatite (Calcium Phosphate) - Ca5(PO4)3(F,Cl,OH)

Turquoise (Dyed Howlite or Magnesite imitation)

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

Chert (often called Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Pegmatite (Granitic)

Granitic Pegmatite containing Quartz, Feldspar, and Tourmaline (Schorl)

Sunstone

Oligoclase or Andesine (Plagioclase Feldspar) - (Ca, Na)((Al, Si)2Si2O8)

Howlite

Calcium Borosilicate Hydroxide (Ca2B5SiO9(OH)5)

Quartz (Peach/Orange variety)

Silicon Dioxide (SiO2)

Sodalite

Sodalite (Na8(Al6Si6O24)Cl2)