Tektite (Natural Glass)

Blue chalcedony (likely dyed or coated)

Microcrystalline quartz, SiO₂ (chalcedony)

Amethyst cabochon

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

Milky Quartz with Iron Inclusions

Silicon Dioxide (SiO2) with Hematite/Limonite

Quartz Pebble

Silicon Dioxide (SiO2)

Polished honey-yellow quartz-like crystal

Quartz (SiO₂), possibly citrine or heat-treated amethyst

Sandstone

Arenite (SiO2 primarily)

Quartz Pebble

Silicon Dioxide (SiO2)

Smoky Quartz

Silicon Dioxide (SiO2)

Lemon Quartz (Orizaba/Citrinated Quartz)

Silicon Dioxide (SiO2) with iron impurities/treatment

Amethyst

Silicon Dioxide (SiO2) with iron impurities

Blue Quartzite (likely dyed)

Silicon dioxide (SiO2) with likely color treatment

Banded Agate (Dyed Purple)

Agate (Variety of Chalcedony/Quartz), SiO2

Green Aventurine

Silicon Dioxide (SiO2) with Fuchsite inclusions

Sandstone

Arenite

Sandstone (Ferruginous)

Arenite (composed primarily of SiO2 with Fe2O3 cement)

Sandstone (Quartzose)

Arenite (primarily SiO2)

Sandstone (Ferruginous)

Arenite (primarily SiO2 with iron oxide cement)

Sandstone

Arenite (SiO2 principal)

Sandstone

Arenite (SiO2 primarily)

Sandstone

Clastic Sedimentary Rock (primarily SiO2)

Polished black pebble, likely basalt

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

Sandstone

Arenite (SiO2 with various cementing agents)

Green faceted bead strand, likely dyed or synthetic material

Uncertain; possibly green-dyed quartz, glass, or lab-created emerald-like material

Cut colorless gemstone, likely quartz or glass imitation

Most plausibly rock crystal (clear quartz, SiO₂); synthetic glass cannot be ruled out from the image

Polished black-and-white stone, possibly snowflake obsidian

Likely obsidian (volcanic glass); exact identification is uncertain from the photo

Libyan Desert Glass

Natural Silica Glass (SiO2 with minor iron and titanium)

Opalite

Synthetic Glass (Amorphized Silicon Dioxide)

Citrine (Tumbled Quartz)

Silicon Dioxide (SiO2)

Yellow Quartz Pebble (Citrine or Iron-Stained Quartz)

Silicon Dioxide (SiO2)

Tumbled carnelian

Carnelian, a translucent orange-red variety of chalcedony (microcrystalline quartz), SiO₂

Clear Quartz Crystal (Rock Crystal)

Quartz (Silicon Dioxide, SiO2)

Quartz Veined Quartzite or Sandstone

Quartzite with Quartz Veins (SiO2)

Small polished dark mineral or gemstone fragment

Indeterminate; possibly smoky quartz, obsidian, or dark tourmaline

Goldstone (Red)

Aventurine Glass

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Chert (Yellow Jasper)

Silicon dioxide (SiO2) with iron oxide inclusions

Quartzite Pebble

Quartzite

Heart-shaped Jasper / Chert Pebble

Microcrystalline Quartz (SiO2)

Flint / Chert Nodule

Microcrystalline quartz (SiO2)

Chert (Jasper)

Silicon Dioxide (SiO2)

Sandstone (Ferruginous)

Arenite with Iron Oxide cement

Red chalcedony (likely dyed or heat-treated)

Microcrystalline quartz, SiO₂; possibly red agate/carnelian