Mineral (Specifically A Variety Of Chalcedony, Which Is Microcrystalline Quartz)

Picture Jasper

Silicon Dioxide (SiO2) with iron oxide inclusions

Granite Pegmatite with Tourmaline and Muscovite

Pegmatite (Feldspar: KAlSi3O8, Quartz: SiO2, Schorl: NaFe2+3Al6(Si6O18)(BO3)3(OH)3(OH))

Fossil Shark Tooth (Otodus obliquus)

Otodus obliquus; hydroxyapatite (mineralized form Ca5(PO4)3(OH))

Milk Quartz (Tumbled Pebble)

Quartz (Silicon Dioxide, SiO2)

Banded Calcite (often sold as 'Mexican Onyx' or 'Calcite Onyx')

Calcite (Calcium Carbonate, CaCO3)

Jasper

Silicon dioxide (SiO2) with impurities

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Sandstone Chert Concretion

Silica-cemented Concretion (primarily SiO2)

Chert (Iron-stained)

Microcrystalline Quartz (SiO2)

Green Aventurine

Aventurine Quartz (SiO2 with Fuchsite inclusions)

Tree Agate

Dendritic Agate (Silicon Dioxide, SiO2)

Milky Quartz with Dendritic Inclusions

Silicon Dioxide (SiO2)

Sandstone (Ferruginous)

Arenite (composed primarily of SiO2 with iron oxide Fe2O3 cement)

Quartz (possibly milky quartz or quartz with inclusions)

SiO2 (Silicon Dioxide)

Jasper (Banded Jasper)

Silicon Dioxide (SiO2) with impurities

Obsidian (specifically Mahogany Obsidian)

Volcanic glass (high silica content, SiO2)

Quartzite

Quartzite (primarily SiO2)

Granite

Granite (Felsic Plutonic Rock)

Sandstone with Secondary Mineral Encrustation

Arenite with Silica/Calcite deposits (SiO2 or CaCO3)

Carnelian

Carnelian (Silica, SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Chert (Yellow Jasper)

Microcrystalline Quartz (SiO2)

Mahogany Obsidian

Obsidian (Volcanic Glass) with Hematite or Magnetite inclusions, SiO2 (Silicon Dioxide)

Chert (often called Jasper in this color)

Microcrystalline quartz (SiO2)

Chert (often called Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Quartz Geode

Silicon Dioxide (SiO2) in a Secondary Sedimentary/Volcanic cavity

Milky Quartz

Silicon Dioxide (SiO2)

Quartz (Iron-stained or Milky Quartz)

Silicon Dioxide (SiO2)

Chert (specifically Flint Arrowhead)

Silicon dioxide (SiO2) - Microcrystalline Quartz

Green Aventurine

Silicon Dioxide (Quartz) with Fuchsite inclusions (K(Al,Cr)2(AlSi3O10)(OH)2)

Chert (Jasper/Chalcedony variety)

Silicon Dioxide (SiO2)

Moss Agate

Silicon Dioxide (SiO2) with inclusions of manganese or iron oxides

Blue Sapphire

Corundum (Al2O3 with trace amounts of iron and titanium)

Limestone (specifically Fossiliferous or Crinoidal Limestone)

Calcium Carbonate (CaCO3) - Calcite Rock

Raw Citrine (Yellow Quartz)

Citrine / Silicon Dioxide (SiO2)

Chert (Jasper/Flint variety)

Microcrystalline Quartz (SiO2)

Leopard Skin Jasper

Jasper (Silicon Dioxide with impurities), SiO2

Black Onyx

Chalcedony (SiO2) with parallel banding