Crystal

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Amethyst

Amethyst (Varietal of Quartz), SiO2 with traces of Iron (Fe3+)

Quartz Geode

Silicon Dioxide (SiO2)

Alexandrite (or Quartz with Chrysoberyl/Phenakite crystal form / Feldspar inclusions)

Chrysoberyl (BeAl2O4) or Quartz (SiO2)

Quartz Geode in Sedimentary Host Rock

Silicon Dioxide (SiO2) in Carbonate Matrix

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Porphyritic Andesite (often called Chinese Writing Stone)

Porphyritic Basaltic Andesite with Feldspar Phenocrysts

Diamond in Kimberlite

Kimberlite Matrix with Carbon (Diamond)

Amethyst quartz cluster

Quartz, SiO₂; purple variety colored mainly by iron impurities and irradiation

Corundum (Ruby/Sapphire crystal)

Al2O3 (Aluminum Oxide)

Quartz Geode

Silicon Dioxide (SiO2) in a sedimentary host

Porphyritic Basalt (Drill Core)

Porphyritic Basalt with Plagioclase Phenocrysts

Ametrine

Silicon Dioxide (SiO2) with iron impurities

Small quartz crystal cluster (likely druzy quartz)

Quartz, silicon dioxide (SiO₂)

Milky quartz (rough quartz crystal)

Quartz, silicon dioxide (SiO₂)

Tsavorite Garnet

Grossular Garnet, Ca3Al2(SiO4)3

Pyrite

Iron Sulfide (FeS2)

Amethyst Geode Cathedral

Amethyst (Silicon Dioxide - SiO2 with Iron impurities)

Pyrite (on Quartz matrix)

Iron Sulfide (FeS2)

Black Tourmaline

Schorl (NaFe2+3Al6(Si6O18)(BO3)3(OH)4)

Tourmalinated Quartz or Schorl

Silicate mineral, specifically Schorl (NaFe2+3Al6(Si6O18)(BO3)3(OH)4) or dark Tourmaline crystal cluster

White quartz cluster

Quartz (silicon dioxide, SiO₂), likely a drusy or microcrystalline cluster

Tumbled quartz-rich pebble

Microcrystalline quartz/chalcedony, SiO₂ (tentative)

Milky quartz-rich rock

Quartz, SiO₂; possibly quartzite or massive vein quartz

Quartz with Epidote / Chlorite Inclusions

Silicon Dioxide (SiO2) with Epidote Ca2(Al,Fe)3(SiO4)3(OH)

Obsidian

Obsidian (Volcanic Glass, SiO2)

Druzy Quartz Geode (Vug)

Silicon Dioxide (SiO2)

Mixed collection of Quartz varieties, Chalcedony, and metamorphic pebbles

Mixed gemstones (primarily Silicon Dioxide - SiO2)

Porphyritic Basalt

Porphyritic Basalt (with Plagioclase phenocrysts)

Milky quartz (rough crystal)

Quartz, silicon dioxide (SiO₂)

Orange stilbite (zeolite) crystal cluster

Stilbite-Ca, hydrated calcium sodium aluminosilicate; approximately (Na,Ca)₉(Si₃₀Al₆)O₇₂·28H₂O

Likely calcite crystal fragment

Calcite (CaCO₃), probably a rhombohedral cleavage fragment

Honey calcite crystal cluster

Calcite (calcium carbonate, CaCO₃)

Large calcite crystal cluster

Calcite (calcium carbonate, CaCO₃)

Quartz Geode/Vug in Host Rock

SiO2 (Silicon Dioxide) in various host rocks

Small rough quartz-family crystal specimens, including likely amethyst and citrine

Quartz, silicon dioxide (SiO₂); purple specimen is likely amethyst, yellow specimen likely citrine or iron-stained quartz

Clear Quartz

Silicon Dioxide (SiO2)

Smoky Quartz (with possible Garnet inclusions)

Silicon Dioxide (SiO2)

Rose Quartz

Silicon Dioxide (SiO2) with trace impurities of Titanium, Iron, or Manganese

Golden Sheen Obsidian

Obsidian (volcanic glass) with inclusions of gas bubbles and mineral crystals (e.g., hematite, magnetite) causing the sheen

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)