Mineral (Synthetic Glass)

Obsidian

Volcanic Glass (SiO2 - Silicon Dioxide with impurities)

Obsidian

Volcanic glass

Black Obsidian

Volcanic Glass (SiO2)

Milky quartz

Quartz (silicon dioxide, SiO₂)

Polished black stone, possibly obsidian or black jasper

Indeterminate; likely volcanic glass (obsidian, SiO₂) or microcrystalline quartz (jasper, SiO₂)

Polished black mineral or volcanic glass fragment

Indeterminate; possibly obsidian or black tourmaline

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

Industrial vitreous slag; primarily amorphous silicate glass, composition variable

Tumbled amber-colored glassy mineral specimens

Likely citrine or yellow chalcedony; exact identification is uncertain from the photograph

Blue glassy mineral fragment, possibly kyanite or blue quartz

Indeterminate from image; candidates include kyanite (Al₂SiO₅) or blue quartz (SiO₂)

Obsidian

Volcanic glass (SiO2 - Silicon Dioxide)

Likely smoky quartz or quartz-rich tumbled fragment

Quartz, silicon dioxide (SiO₂), possibly smoky quartz

White quartz-rich pebble, possibly chalcedony or milky quartz

Quartz (SiO₂), potentially microcrystalline quartz (chalcedony)

Milky quartz

Quartz (silicon dioxide, SiO₂)

Polished mahogany obsidian (likely)

Volcanic glass; rhyolitic obsidian, predominantly amorphous SiO₂

Obsidian

Volcanic glass (SiO2 + impurities)

Obsidian

Obsidian (Volcanic Glass, SiO2 + impurity)

Obsidian

Extrusive igneous volcanic glass (rich in SiO2)

Obsidian

Extrusive igneous volcanic glass

White Quartz Star

Silicon Dioxide (SiO2)

Greenish quartz (likely prase/chalcedony)

Quartz, SiO₂; possibly green chalcedony or chlorite-included quartz

Clear Quartz

Silicon dioxide (SiO2)

White Quartz

Silicon Dioxide (SiO2)

Milky quartz (rough quartz fragment)

Quartz, silicon dioxide (SiO₂)

Beaded gemstone jewelry (likely amethyst, lapis lazuli, and pearl or glass imitation)

Mixed mineral beads; possible quartz (SiO₂) and lazurite-bearing lapis lazuli

Quartz-rich rock, possibly milky quartz or quartzite

Quartz (SiO₂), likely with minor iron-oxide or feldspar inclusions

Greenish translucent glassy mineral specimen, possibly fluorite or quartz

Likely fluorite (CaF₂) or green quartz (SiO₂); exact identification requires hardness and cleavage tests

Quartz Geode (with possible Manganese or Goethite coating)

Silicon Dioxide (SiO2)

Pegmatite (with Muscovite Mica and Quartz)

Granitic Pegmatite (chiefly KAlSi3O8, SiO2, and KAl2(AlSi3O10)(OH)2)

Quartz on Schist

Silicon Dioxide (SiO2) on Foliated Metamorphic Rock

Tumbled Quartz

Silicon Dioxide (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Quartz

Silicon Dioxide (SiO2)

K-Feldspar (Potassium Feldspar)

Orthoclase / Microcline (KAlSi3O8)

Polished blue calcite sphere (tentative identification)

Calcite, CaCO₃; blue color generally results from trace impurities or inclusions

Blue Obsidian (Cullet Glass)

Silicon Dioxide (Amorphous Glass)

Sheen Obsidian

Volcanic glass (SiO2 with inclusions)

Blue glassy mineral fragment, likely kyanite or blue corundum

Tentatively kyanite (Al₂SiO₅); visual identification is uncertain from the photograph

Greenish translucent mineral fragment, possibly aventurine quartz or fluorite

Uncertain from image; likely quartz (SiO₂) with inclusions, or fluorite (CaF₂)

Green obsidian (likely molded or heat-treated glass-like specimen)

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

Quartz (Granular)

Silicon Dioxide (SiO2)

Quartz Pebbles

Silicon Dioxide (SiO2)

Goldstone (blue-goldstone–style glass) beads

Artificial aventurine glass, typically silica glass with copper inclusions; not a natural mineral