Man Made Glass

Tumbled black stone, likely black obsidian

Obsidian (volcanic glass; chiefly silica-rich rhyolitic composition)

Tumbled quartz pebble

Quartz, silicon dioxide (SiO₂), likely milky quartz

Blue Glass or Slag Glass

Amorphous Silica (Anthropogenic Glass)

Polished milky quartz (likely quartz worry stone or wand)

Quartz, silicon dioxide (SiO₂)

White quartz pebble

Quartz (SiO₂), likely milky quartz

Sea Glass (White/Clear)

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

Polished black stone, likely black obsidian

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

Green Aventurine

Silicon Dioxide (SiO2) with inclusions of Fuchsite (K(Al,Cr)2AlSi3O10(OH)2)

Blue Goldstone

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

Tumbled milky quartz

Quartz (SiO₂), cryptocrystalline-to-massive variety

Tumbled milky quartz pebble

Quartz (silicon dioxide, SiO₂), opaque-to-translucent milky variety

Blue opal heart cabochon

Common opal, hydrated amorphous silica (SiO₂·nH₂O), likely blue-dyed or synthetic opalite

Sea Glass

Amorphous silicon dioxide (Man-made glass weathered by nature)

Green Aventurine

SiO2 (Silicon Dioxide with Fuchsite inclusions)

Polished labradorite sphere

Labradorite, calcic plagioclase feldspar ((Ca,Na)(Al,Si)₄O₈)

Polished labradorite pendant

Labradorite, a calcium-rich plagioclase feldspar (approximately NaAlSi₃O₈–CaAl₂Si₂O₈)

Sea Glass

Amorphous Silicon Dioxide (Man-made glass weathered by nature)

Blue-green cabochon, likely chalcedony or treated glass imitation

Cryptocrystalline quartz (chalcedony/possibly chrysoprase); identification uncertain from image

Green Quartz / Chrysoprase / Sea Glass

Silicon Dioxide (SiO2)

Cullet Glass (Man-made Glass Slag)

Amorphous Silica (SiO2) with chemical additives

Tumbled white chalcedony (likely milky quartz)

Chalcedony, microcrystalline quartz (SiO₂)

Polished brown jasper (likely brecciated or orbicular jasper)

Microcrystalline quartz/chalcedony, SiO₂, with iron-oxide and other mineral inclusions

Green Aventurine

Silicon Dioxide (Quartz with Fuchsite inclusions), SiO2

Clear quartz sphere

Quartz (silicon dioxide, SiO₂)

Cobalt Glass Slug (Man-made Glass)

Amorphous Silica with Cobalt Oxide (SiO2 + CoO)

Clear quartz fragment

Quartz (silicon dioxide, SiO₂)

Polished dendritic agate or jasper

Microcrystalline quartz (SiO₂), likely chalcedony with iron/manganese dendrites

Milky quartz (likely rough quartz crystal)

Quartz, silicon dioxide (SiO₂)

Polished black pebble, likely basalt

Basalt, a fine-grained mafic volcanic rock composed mainly of plagioclase feldspar and pyroxene, commonly with olivine

Black Obsidian

Amorphous volcanic glass (SiO2 + impurities)

Opalite

Synthetic Opalised Glass

Aventurine Quartz

Silicon Dioxide (SiO2) with Fuchsite inclusions

Sea Glass

Amorphous silicon dioxide (SiO2) - Man-made glass tumbled by nature

Strawberry Quartz

Silicon Dioxide (SiO2) with Hematite or Goethite inclusions

Moldavite

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

Likely clear quartz pebble or glassy quartz fragment

Quartz (silicon dioxide, SiO₂)

Polished silver sheen obsidian heart

Obsidian (volcanic glass), primarily rhyolitic silica-rich glass

Blue glassy fragment among beach gravel

Likely cobalt-blue man-made glass; not a natural mineral specimen

Green Sea Glass

Amorphous Silica (man-made glass), SiO2 + additive metal oxides

Milky quartz (rough quartz fragment)

Quartz, silicon dioxide (SiO₂)

Clear quartz fragment (rock crystal)

Quartz, silicon dioxide (SiO₂)

Rock crystal (clear quartz), possibly cloudy quartz

Quartz, silicon dioxide (SiO₂)