Glass

Green faceted gemstone, likely synthetic glass or peridot

Indeterminate from image; possible peridot (olivine, (Mg,Fe)₂SiO₄) or green synthetic glass

Pumice

Pumice (Vesicular Felsic Igneous Rock)

Clear Quartz (Cut/Faceted Gemstone)

Silicon Dioxide (SiO2)

Iron Slag

Anthropogenic Iron Silicate

Opalite

Man-made glass (traditionally simulated Opal)

Terrazzo (Synthetic Composite Rock)

Cementitious or Epoxy Resin-bound Aggregates

Tumbled quartz-rich pebble, possibly smoky quartz or chert

Quartz (SiO₂), or microcrystalline quartz if chert

Quartz vein rock with iron-oxide staining

Milky quartz (SiO₂), locally stained by hematite/goethite; possible feldspar or host-rock fragments

Quartz (Milky/Gravel variety)

Silicon Dioxide (SiO2)

Sandstone

Arenite (Clastic Sedimentary Rock)

Blue chalcedony cabochon (probable)

Chalcedony, cryptocrystalline quartz; silicon dioxide (SiO₂)

Chert (variations include Flint/Jasper)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Tumbled rose quartz (likely)

Quartz, silicon dioxide (SiO₂), probably rose quartz

Quartz-rich pegmatite, possibly with feldspar and mica

Granitic pegmatite; mainly quartz (SiO₂), feldspar, and mica

Green Slag Glass

Amorphous Silicon Dioxide (with metallic impurities)

Smoky Quartz

Silicon Dioxide (SiO2)

Opalite glass sphere (likely synthetic imitation)

Man-made opalescent glass; not natural opal

Goldstone (Red/Brown)

Aventurine Glass (SiO2 with Copper inclusions)

Rounded quartz-rich beach pebble

Likely milky quartz or quartzite (SiO₂)

Tumbled amethyst

Quartz, SiO₂; purple variety colored mainly by iron-related defects

Tumbled amethyst

Amethyst, purple quartz (SiO₂)

Amethyst quartz

Quartz, silicon dioxide (SiO₂), purple variety colored mainly by iron-related defects

Quartz (specifically Milky or Clear Quartz)

Silicon Dioxide (SiO2)

Tumbled smoky quartz with iron-stained inclusions

Quartz (SiO₂), likely smoky quartz variety

Titanium Coated Aura Quartz (Apple Aura Quartz)

Silicon Dioxide (SiO2) with Metallic Vapor Deposition Coating

Quartz-rich rock, likely milky quartz

Quartz (silicon dioxide, SiO₂), possibly a quartzite fragment

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Small clear crystal, possibly quartz or glass-like gemstone

Uncertain; likely quartz (SiO₂), but the image is insufficient to exclude man-made glass or cubic zirconia

Likely fluorite fragments

Fluorite (calcium fluoride, CaF₂)

Man-made Glass (Tumbled/Shaped)

Amorphous Silicon Dioxide (SiO2) with metal oxide colorants

Tumbled milky quartz pebbles

Quartz (silicon dioxide, SiO₂)

Polished red jasper mushroom carving

Jasper, microcrystalline quartz (SiO₂), colored chiefly by iron oxides

Tumbled amethyst

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

Smoky quartz (rough, water-worn crystal)

Quartz, silicon dioxide (SiO₂), smoky variety

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Flint (Chert)

Silicon Dioxide (SiO2)

Quartz

Silicon Dioxide (SiO2)

Likely polished chalcedony or agate cabochon pendant

Microcrystalline quartz, SiO₂ (chalcedony/possibly banded agate)

Clear Quartz

Quartz (Silicon Dioxide, SiO2)

Chert (or Jasper)

Cryptocrystalline Quartz (SiO2)

Smoky Quartz (with Iron Inclusions)

Silicon Dioxide (SiO2)

Rounded river pebble, likely sandstone or weathered quartzite

Indeterminate lithic clast; probable quartz-rich sandstone (SiO₂-dominant)