Tektite (Natural Glass)

Citrine Quartz

Macrocrystalline Quartz (SiO2)

Colorless quartz crystal (likely quartz fragment)

Quartz, silicon dioxide (SiO₂)

Green cabochon gemstone pendant, likely turquoise or dyed green turquoise

Probably turquoise, CuAl₆(PO₄)₄(OH)₈·4H₂O; exact identification requires testing

Red cabochon gemstone ring, likely synthetic ruby or red glass

Possibly corundum (Al₂O₃, chromium-colored); identity cannot be confirmed from the image

Jasper

Silicon dioxide (SiO2)

Goldstone (Red)

Aventurine Glass (Cupriferous glass)

Tumbled amethyst

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

Citrine Quartz

Citrine (Silicon Dioxide, SiO2)

Citrine

Citrine (Silicon Dioxide, SiO2)

Obsidian

Volcanic Glass (Amorphous silicon dioxide with trace impurities)

Quartz (Smoky/Brown variety)

Silicon dioxide (SiO2)

Green glassy slag (often sold as “sea glass” or “green obsidian”)

Industrial vitreous slag; primarily amorphous silicate glass, composition variable

Aventurine

Silicon Dioxide (SiO2 with inclusions of Fuchsite mica)

Mahogany Obsidian

Volcanic Glass with Hematite/Magnetite inclusions (SiO2 + Fe2O3)

Obsidian

Obsidian (Volcanic Glass) SiO2 (70% or more)

Goldstone

Aventurine Glass (SiO2 + Cu small inclusions)

Quartzite pebble

Quartzite (SiO2)

Yellow Quartz (Citrine or Iron-stained Quartz)

Silicon Dioxide (SiO2)

Opalite

Opalescent Glass (SiO2 + coloring agents)

Yellow Quartz / Citrine Pebble

Silicon Dioxide (SiO2)

Snowflake Obsidian

Volcanic Glass (SiO2 with Cristobalite inclusions)

Tumbled amethyst

Quartz, purple variety; silicon dioxide (SiO₂) colored mainly by iron-related defects

Goldstone (Brown/Gold)

Aventurine Glass (Man-made glass with Copper inclusions)

Pearl oyster shell with natural pearls

Molluscan shell, likely Pinctada spp.; pearls are aragonite (CaCO₃)

Blue slag glass / industrial smelter slag

Man-made iron-rich silicate slag; composition variable, commonly Fe–Ca–Mg–Al silicates with glassy phases

Milky quartz pebble

Quartz (silicon dioxide, SiO₂)

Tumbled pale-yellow quartz (likely citrine or iron-stained quartz)

Quartz, silicon dioxide (SiO₂); yellow color likely from iron-related impurities

Red glass-like crystal, likely synthetic ruby or red glass

Uncertain from image; possible corundum (ruby), Al₂O₃, or synthetic glass

Green sea glass or tumbled green quartz (uncertain)

Likely quartz (SiO₂) if natural; alternatively man-made soda-lime glass

Quartz (likely milky quartz or quartz glass-like fragment)

Quartz, silicon dioxide (SiO₂)

Chert (Vuggy or Weathered)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Quartz

Silicon Dioxide (SiO2)

Chert Concretion (Flint)

Silicon Dioxide (SiO2)

Dyed Quartz Pendant

Silicon Dioxide (SiO2) with artificial dye

Sandstone

Clastic Sedimentary Rock

Citrine (tumbled)

Silicon dioxide, SiO2

Blue faceted gemstone ring, likely synthetic sapphire or blue topaz

Uncertain from image; possible corundum (Al₂O₃) or topaz (Al₂SiO₄(F,OH)₂)

Green glass-like mineral specimen, likely fluorite

Fluorite (calcium fluoride, CaF₂), if natural; appearance may also indicate colored glass

Sandstone

Clastic Sedimentary Rock

Quartz pebble

Silicon dioxide (SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Milky quartz fragment (likely quartz-rich mineral)

Quartz, silicon dioxide (SiO₂)