Tektite (Natural Glass)

Likely tumbled quartz-rich pebble

Quartz (SiO₂), possibly a weathered quartzite or chalcedony pebble

Quartz Sandstone

Quartz Arenite

Quartz Druzy

Crystalline Silicon Dioxide (SiO2)

Quartz (Citrine or Iron-stained variety)

Silicon Dioxide (SiO2)

Amethyst Quartz

Amethyst (Silicon Dioxide, SiO2)

Beach Agate / Jasper Pebble

Cryptocrystalline Quartz (SiO2)

Aquamarine with Ruby Accent

Beryllium Aluminum Silicate (Be3Al2Si6O18) with Aluminum Oxide (Al2O3)

Sandstone

Arenite (SiO2 primarily)

Sandstone (Quartzose)

Arenite (primarily SiO2)

Citrine

Silicon Dioxide (SiO2) with iron impurities

Pink Tumbled Agate

Silicon Dioxide (SiO2) with dye

Smoky Quartz

Silicon Dioxide (SiO2)

Blue quartz-like mineral specimen

Likely quartz (SiO₂), possibly dyed or coated; exact identification requires testing

Blue-green turquoise-like tumbled stone

Turquoise, hydrous copper aluminum phosphate: CuAl₆(PO₄)₄(OH)₈·4H₂O

Green Aventurine

Aventurine Quartz (SiO2 with Fuchsite inclusions)

Green Aventurine

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

Green Aventurine

Aventurine Quartz (SiO2 with Fuchsite inclusions)

Quartz Pebble (Sea Glass-like Quartz)

Quartz (Silicon Dioxide - SiO2)

Yellow Quartz / Quartz Pebble

Silicon Dioxide (SiO2)

Sandstone (Pebble)

Arenite (SiO2 based)

Pumice

Pumicite (Volcanic glass with vesicular texture)

Green Glass Slag

Amorphous Silicon Dioxide (SiO2) with metal oxide impurities

Citrine

Silicon dioxide (SiO2)

Garnet and Quartz

Pyrope or Almandine (Red Garnets) and Quartz (Center Stone)

Goldstone (with Tiger's Eye and Quartz)

Aventurine glass (Synthetic SiO2 with Cu inclusions)

Slag (Industrial Byproduct)

Ferro-silicate glass (Slag)

Green Aventurine

Silicon Dioxide (SiO2) with inclusions of Fuchsite

Mahogany Obsidian

Natural Volcanic Glass (SiO2 with iron and magnesium oxides)

Agate (Water-Worn)

Cryptocrystalline quartz (SiO2)

Obsidian with Perlitic Crust

Volcanic Glass (SiO2)

Black Onyx

Silicon Dioxide (SiO2)

Smoky Quartz (with inclusions)

Silicon Dioxide (SiO2)

Clear Quartz Sphere

Silicon Dioxide (SiO2)

Quartz (Citrine or Iron-Stained)

Silicon Dioxide (SiO2)

Smoky Quartz

Smoky Quartz (Silicon Dioxide, SiO2)

Yellow Sapphire (Corundum)

Corundum (Aluminum Oxide, Al2O3)

Granite Pebble

Granite; primarily composed of Quartz (SiO2), Feldspar (KAlSi3O8), and Mica

Sandstone

Arenite

Smoky Quartz

Silicon Dioxide (SiO2)

Yellow Quartz (Citrine or Yellow Jasper)

Silicon Dioxide (SiO2) with iron impurities

Yellow Quartz

Silicon Dioxide (SiO2)

Tumbled yellow chalcedony (likely citrine or yellow jasper)

Microcrystalline quartz, SiO₂; exact identification is uncertain from the photograph