Mineraloid (Man Made Glass)

Polished black stone, likely black obsidian

Volcanic glass; predominantly rhyolitic silica glass (SiO₂-rich)

Sea Glass

Man-made vitreous material (silica-based glass)

Tumbled clear quartz (rock crystal)

Quartz, silicon dioxide (SiO₂)

Slag

Anthropogenic glassy silicate

Clear quartz crystal (likely)

Quartz, silicon dioxide (SiO₂)

White quartz pebble or chip

Quartz (silicon dioxide, SiO₂), possibly milky quartz

Unidentified translucent crystal/mineral fragment

Likely quartz (SiO₂), but visual identification is uncertain

Green Aventurine

Silicon Dioxide (Quartz with Fuchsite inclusions), SiO2

Pink Quartz / Sea Glass

Silicon Dioxide (SiO2)

Slag Glass

Vitreous Silicate Residue

Pearl (Biogenic Mineraloid)

Calcium carbonate (CaCO3) primarily as Aragonite

Goldstone (Red)

Aventurine Glass (Cupriferous glass)

Sea Glass

Man-made silicate glass (Amorphous silicon dioxide)

Opalite (Man-made Glass)

Synthetic Silicon Dioxide Glass (SiO2 + metal oxides)

Opalite (Man-made Glass)

Fused glass (typically made of dolomite and metal opacifiers)

Slag Glass

Anthropogenic Amorphous Silicon Dioxide

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

Quartz, silicon dioxide (SiO₂)

Libyan Desert Glass

Tektite (high-silica impact glass), SiO2

Blue Glass or Slag Glass

Amorphous Silica (Anthropogenic Glass)

Precious Coral (Red Coral)

Corallium rubrum (Calcium Carbonate, CaCO3)

Opalite

Synthetic Opalised Glass

White sea glass (naturally frosted glass fragment)

Man-made silicate glass, typically soda-lime glass; not a mineral or rock

Stainless Steel (Polished)

Ferrous Alloy containing Iron (Fe), Chromium (Cr), and Carbon (C)

Tumbled opalite (likely man-made glass)

Opalite, a trade name for opalescent glass; not natural opal

Black tumbled stone, possibly obsidian

Obsidian (volcanic glass; predominantly SiO₂), identification uncertain from image

Clear quartz sphere

Quartz (silicon dioxide, SiO₂)

Libyan Desert Glass

Libyan Desert Glass (SiO2 with trace elements)

Sea Glass (White/Clear)

Amorphous Silica (Alkali-Lime-Silica Glass), SiO2 + Na2O + CaO

Chert (Arrowheads)

Microcrystalline Quartz (SiO2)

Tumbled clear quartz (rock crystal)

Quartz, silicon dioxide (SiO₂)

Glass Nugget (Tumbled Glass)

Amorphous Silicon Dioxide (SiO2) with additives

Clear quartz tumbled stone

Quartz (silicon dioxide, SiO₂)

Tumbled milky quartz pebble

Quartz (silicon dioxide, SiO₂)

Obsidian (Blue)

Volcanic Glass (SiO2)

Strawberry Quartz

Silicon Dioxide (SiO2) with Hematite or Goethite inclusions

Blue glassy gemstone cabochon, likely dyed chalcedony or glass

Uncertain; possible dyed chalcedony (microcrystalline quartz, SiO₂)

Blue cabochon gemstone, likely synthetic glass or dyed stone

Indeterminate from image; possible glass, synthetic spinel, sodalite, or lapis lazuli

Blue Goldstone

Man-made glass with suspended copper, cobalt, or manganese particles

Green sea glass or tumbled green quartz (uncertain)

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

Clear quartz fragment (rock crystal)

Quartz, silicon dioxide (SiO₂)

Exposed Aggregate Concrete (Pea Gravel)

Concrete with Siliceous Alluvial Gravels

Moldavite

Tektite (Impact Glass), ~80% SiO2 + Al2O3