Organic Gemstone (Not A Rock)

Blue Lace Agate

Chalcedony (cryptocrystalline variety of Quartz), SiO2

Chert (Iron-stained)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Green Fluorite

Fluorite (Calcium Fluoride, CaF2)

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Pyrite (Iron Pyrite)

Iron Disulfide (FeS2)

Anthracite Coal

Anthracite (Carbon-based metamorphic rock)

Muscovite Mica

Muscovite - KAl2(AlSi3O10)(OH)2

Sodalite

Sodalite (Na8(Al6Si6O24)Cl2)

Sedimentary Breccia

Clastic Breccia (CaCO3/SiO2 matrix)

Basalt

Mafic volcanic rock (Silicon dioxide 45-52%)

Dzi Bead (Etched Chalcedony)

Cryptocrystalline Quartz (SiO2) with chemical etching

Sandstone (Pet Rock)

Clastic sedimentary rock (primarily SiO2)

Chert (specifically River Stone / Jasper variety)

Microcrystalline Quartz (SiO2)

Basalt Pebble with Epidote/Olivine

Vitreous Basalt (SiO2 with Ca/Mg/Fe silicates)

Gneiss

Gneiss (High-grade metamorphic rock)

Basalt

Mafic Igneous Rock (primarily Plagioclase Feldspar and Pyroxene)

Limonite (Iron Ore Congcretion)

Limonite (a mixture of hydrated iron(III) oxide-hydroxides, FeO(OH)·nH2O)

Quartz / Common Opal

Silicon Dioxide (SiO2)

Gold Ore in Quartz

Native Gold (Au) in Quartz (SiO2)

Basalt (Water-worn Pebble)

Basalt (Aphanitic Mafic Igneous Rock)

Red Quartzite

Quartzite (primarily SiO2)

Amethyst

Crystalline Silicon Dioxide with Iron impurities (SiO2)

Carnelian (Banded Agate)

Chalcedony (SiO2) with Iron Oxide inclusions

Chert (Smooth River Pebble)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Vanadinite

Lead Chlorovanadate, Pb5(VO4)3Cl

Basalt

Basalt (Mafic volcanic rock)

Basalt (Road Aggregate / Crushed Stone)

Aphanitic Mafic Igneous Rock

Basalt

Basalt (comprising plagioclase, pyroxene, and olivine)

Quartzite

Quartzite (primarily SiO2)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Jasper (specifically Yellow/Red Jasper)

Silicon Dioxide (SiO2) with iron oxide inclusions

Quartzite

Quartzite (SiO2 silicon dioxide)

Quartzite

Quartzite (primarily SiO2)

Black Obsidian

Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)

Ferruginous Slag (Iron Smelting Byproduct)

Fused Silicate Scoria (Amorphous mixture of FeO, SiO2, and CaO)

Stichtite in Serpentine (Atlantisite)

Mg6Cr2CO3(OH)16·4H2O (Stichtite) / Mg3Si2O5(OH)4 (Serpentine)

Peach Moonstone

Potassium Aluminum Silicate (KAlSi3O8)

Carnelian Agate

Silicon Dioxide (SiO2) with Iron Oxide impurities

Dendritic Agate

Dendritic Agate (Silicon Dioxide with Manganese or Iron Oxide inclusions, SiO2)

Granite

Phaneritic Felsic Igneous Rock

Dendritic Agate (also known as Dendritic Siltstone or Mudstone)

Silicon Dioxide with Manganese/Iron Oxide inclusions (SiO2 + MnO2)

Yellow Jasper

Silicon Dioxide (SiO2) with Iron inclusions