Crystal

Tumbled blue chalcedony (possibly blue agate)

Microcrystalline quartz, SiO₂; chalcedony variety

Granite Pegmatite

Phaneritic Plutonic Igneous Rock

Herkimer Diamond

Quartz (Silicon Dioxide, SiO2)

Quartz Crystal Cluster on Matrix

Silicon Dioxide (SiO2)

Tiny amber-colored crystal or mineral fragment

Indeterminate from image; possibly quartz, citrine, topaz, or iron-stained feldspar

Quartz crystal cluster (likely iron-stained quartz)

Quartz, silicon dioxide (SiO₂); possibly quartz on a sulfide- or carbonate-rich matrix

Milky Quartz

Silicon Dioxide (SiO2)

Smoky Quartz (with possible Garnet inclusions)

Silicon Dioxide (SiO2)

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

Chrysoberyl (BeAl2O4) or Quartz (SiO2)

Rose Quartz

Silicon dioxide (SiO2) with trace amounts of titanium, iron, or manganese

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Pyrite

Iron Sulfide (FeS2)

Hemimorphite or Red Quartz

SiO2 (Quartz) / Zn4Si2O7(OH)2·H2O (Hemimorphite)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Rose Quartz

Silicon Dioxide (SiO2)

Tumbled and polished quartz crystal points

Quartz (silicon dioxide, SiO₂), chiefly rock crystal with smoky or included varieties

Quartz Geode

Crystalline Silicon Dioxide (SiO2) in Geode

Clear faceted gemstone, likely quartz (rock crystal)

Quartz, silicon dioxide (SiO₂); exact identity cannot be confirmed from the glare-heavy image

Tumbled orange aventurine (likely orange quartzite)

Quartz-rich quartzite, mainly SiO₂; orange color likely from iron-oxide inclusions

Porphyritic volcanic rock, likely porphyritic andesite

Porphyritic andesite (tentative; exact composition cannot be confirmed from the photo)

White quartz crystal cluster (likely druzy quartz)

Quartz, SiO₂; likely a quartz-lined cavity fragment

Possibly pale-green fluorite crystals

Fluorite (calcium fluoride, CaF₂)

Red quartz crystal cluster (likely iron-stained quartz)

Quartz, silicon dioxide (SiO₂), with hematite/goethite staining or inclusions

Quartz Druze

Silicon Dioxide (SiO2)

Likely synthetic ruby (corundum)

Corundum (Al₂O₃), probably laboratory-grown

Tumbled orbicular/patterned jasper (likely brecciated jasper)

Microcrystalline quartz (SiO₂) with iron-oxide and possibly calcite/chalcedony veining

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)

Pyrite (likely)

Iron disulfide, FeS₂; possibly a pyrite-rich sulfide nodule

Milky Quartz with Iron Staining

Quartz (Silicon Dioxide) - SiO2

Quartz Pebble

Silicon Dioxide (SiO2)

Orange Calcite (Dogtooth/Cluster)

Calcium Carbonate (CaCO3)

Black tourmaline (schorl) pendant

Schorl, NaFe₃Al₆(BO₃)₃Si₆O₁₈(OH)₄