Crystal

Quartz Crystal Point

Silicon Dioxide (SiO2)

Clear Quartz Crystal

Silicon Dioxide (SiO2)

Clear Quartz Crystal

Silicon Dioxide (SiO2)

Clear Quartz Crystal

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Obsidian

Obsidian (principally SiO2)

Quartz crystal cluster

Quartz, silicon dioxide (SiO₂), likely milky or partially included rock crystal

Rough garnet-bearing rock (likely almandine garnet in host rock)

Garnet, probably almandine (Fe₃Al₂(SiO₄)₃), in a garnet-bearing metamorphic matrix

Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Clear Quartz Crystal

Silicon Dioxide (SiO2), Quartz

Clear faceted quartz-like gemstone

Probably rock crystal quartz (SiO₂), though the image may show synthetic glass or cubic zirconia

Pyrite (fool’s gold)

Pyrite, iron disulfide (FeS₂)

Polished purple amethyst cabochon

Amethyst, purple variety of quartz (SiO₂)

Rough beryl, possibly emerald

Beryl, Be₃Al₂Si₆O₁₈; green color may be due to chromium or vanadium

Rose Quartz

Silicon Dioxide (SiO2)

Clear Quartz (Facet Cut / Polished)

Silicon Dioxide (SiO2)

Aura Quartz (Titanium/Gold coated)

Silicon Dioxide (SiO2) with metallic vapor deposition

Quartz

Silicon dioxide (SiO2)

Green Aventurine

Quartz (SiO2) with fuchsite inclusions

Quartz with Tourmaline or Amphibole

Silicon Dioxide with silicate inclusions (SiO2)

Tumbled Quartz

Silicon Dioxide (SiO2)

Unidentified transparent crystal or mineral fragment

Cannot be determined from the image; possible quartz, but not diagnostic

Amethyst

Quartz (Silicon Dioxide, SiO2)

Chalcedony with Quartz Crystals

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Quartz-bearing dark mineral specimen

Quartz (SiO₂) on a dark host rock, possibly basalt or sulfide-rich ore

Blue chalcedony cabochon (likely)

Chalcedony, microcrystalline SiO₂; possibly blue agate or common opal, which cannot be distinguished confidently from the image

Quartz (Crystal Cluster)

Silicon Dioxide (SiO2)

Clear Quartz Crystal

Silicon Dioxide (SiO2)

Quartz crystal cluster (likely druzy quartz)

Quartz, silicon dioxide (SiO₂)

Man-made Crystal (Lead Glass)

Lead oxide-doped Silica Glass (approx. SiO2 + PbO)

Halite

Sodium chloride (NaCl)

Sulfur on Aragonite

Sulfur (S) on Aragonite (CaCO3)

Bicolor tourmaline crystal

Elbaite tourmaline, Na(Li₁.₅Al₁.₅)Al₆(BO₃)₃Si₆O₁₈(OH)₄

Amethyst (rough crystal)

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

Quartz Crystal Cluster

Silicon Dioxide (SiO2)

Quartz Crystal Matrix

Silicon Dioxide (SiO2)

Obsidian

Obsidian (Volcanic Glass)

Clear quartz (rock crystal)

Quartz, silicon dioxide (SiO₂)