Mineral Like (Natural Glass)

Tumbled amethyst

Quartz, purple variety; silicon dioxide (SiO₂), colored mainly by iron impurities and irradiation

Tumbled green aventurine (probable)

Quartzite dominated by quartz (SiO₂), with green fuchsite mica inclusions

Polished smoky quartz with iron-oxide inclusions

Quartz (SiO₂), smoky variety; inclusions likely hematite/goethite

Mixed polished and tumbled mineral specimens, prominently amethyst

Amethyst: purple quartz, SiO₂; accompanying pieces may include jasper, agate, aventurine, tiger’s eye, and other lapidary stones

Amethyst cabochon jewelry

Amethyst, purple variety of quartz (SiO₂)

Yellow Quartz (Citrine Quartz Pebble)

Silicon Dioxide (SiO2)

Strawberry Quartz (or Pink Aventurine)

Quartz with Hematite/Goethite inclusions (SiO2)

Green cabochon gemstone, likely glass-filled or synthetic emerald imitation

Uncertain; possible synthetic emerald (beryl, Be₃Al₂Si₆O₁₈) or green glass

Obsidian

Obsidian (Volcanic Glass, SiO2)

Green Aventurine

Silicon Dioxide (SiO2) with inclusions of Fuchsite (K(Al,Cr)3Si3O10(OH)2)

Raw smoky quartz (probable)

Quartz, silicon dioxide (SiO₂), with irradiation-related smoky coloration

Smoky Quartz

Silicon Dioxide (SiO2)

Colorless faceted gemstone (likely glass or cubic zirconia)

Likely cubic zirconia, ZrO₂; exact identification is uncertain from the photograph

Polished tektite (likely indochinite)

Natural silica-rich impact glass; mainly SiO₂ with Al₂O₃, FeO, MgO, CaO, and Na₂O

Asphalt (Bituminous Rock)

Natural bitumen or Bituminous limestone/sandstone

Chert (often colloquially called Flint)

Chert (Microcrystalline Quartz, SiO2)

Snowflake Obsidian

Vitreous volcanic silicate (SiO2 with Cristobalite inclusions)

Mixed landscaping gravel and mineral specimens

Mixed silicate and carbonate rocks; likely quartz, chert, jasper, basalt, granite, and limestone

Amethyst

Amethyst (Silicon Dioxide - SiO2 with iron impurities)

Amethyst

Silicon Dioxide (SiO2) with iron impurities

Milky Quartz

Silicon Dioxide (SiO2)

Green Garden Quartz (Phantom Quartz)

Silicon Dioxide (SiO2) with Chlorite inclusions

Sandstone

Arenite (primarily SiO2)

Blue Chalcedony (likely dyed)

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Citrine Quartz

Silicon Dioxide (SiO2) with iron impurities

Granite (Giallo Ornamental / Venetian Gold)

Granite (composed mainly of Quartz, Feldspar, Biotite, and Garnet)

Diamond (or Lab-Grown Cubic Zirconia)

Carbon (C)

Howlite

Calcium borosilicate hydroxide (Ca2B5SiO9(OH)5)

Citrine Geode Fragment

Silicon Dioxide (SiO2) with iron impurities

Sandstone (with Iron Staining)

Clastic Sedimentary Rock (primarily SiO2 with Fe2O3 oxides)

Red jasper (likely polished or dyed)

Jasper, microcrystalline quartz (SiO₂), commonly colored by iron oxides

Blue Goldstone

Man-made glass with cobalt and metal flecks

Black Freshwater Pearls

Biogenic Calcium Carbonate (Aragonite/Calcite), CaCO3

Red agate-like polished stone (likely dyed chalcedony)

Chalcedony, microcrystalline SiO₂; possibly dyed quartz or glass imitation

Rounded quartz-rich pebble

Lithic pebble; likely quartz/quartzite with iron-oxide staining

Tumbled purple gemstone, likely amethyst

Amethyst, purple variety of quartz (SiO₂)

Yellow Quartz (Citrine type/Tumbled Quartz)

Silicon Dioxide (SiO2)

Tumbled agate/chalcedony

Microcrystalline quartz (SiO₂), likely mossy or dendritic agate

Tumbled amber-colored chalcedony or jasper

Microcrystalline quartz (SiO₂), likely iron-stained chalcedony/jasper

Strawberry Quartz (Hematoid Quartz)

Silicon Dioxide with Hematite/Goethite inclusions (SiO2 + Fe2O3)

Sandstone (with Iron Staining)

Clastic sedimentary rock (primarily Quartz - SiO2)

Pink Dyed Agate Geode Slice

Silicon Dioxide (SiO2) with artificial pigment