Mineral (Man Made Glass)

Quartz (Milky or Citrine-tinted)

Silicon Dioxide (SiO2)

Quartz Pebble (Iron-Stained)

Quartz (Silicon Dioxide - SiO2)

Quartz (Smoky/Grey variety)

Silicon Dioxide (SiO2)

Green Aventurine

Silicon Dioxide (Quartz with Fuchsite inclusions), SiO2 + K(Al,Cr)2AlSi3O10(OH)2

Milky Quartz with Limonite

Silicon Dioxide (SiO2)

Black Obsidian

Volcanic Glass (SiO2)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Citrine

Citrine (Silicon Dioxide, SiO2)

Quartz Crystal with Inclusions

Silicon Dioxide (SiO2)

Smoky Quartz

Silicon Dioxide (SiO2)

Quartz

Silicon Dioxide (SiO2)

Quartz (Clear Quartz/Rock Crystal)

Silicon Dioxide (SiO2)

Clear Quartz

Silicon Dioxide (SiO2)

Citrine

Citrine (Silicon Dioxide - SiO2)

Milky Quartz/Clear Quartz Cluster

Silicon Dioxide (SiO2)

Sandstone (likely with Quartz Veining)

Arenite (primarily SiO2)

Quartz (Milky/Crystalline variety)

Silicon Dioxide (SiO2)

Yellow Quartz (Citrinated Quartz)

Silicon Dioxide (SiO2)

Quartz (Milky/Rose variety)

Silicon Dioxide (SiO2)

Smoky Quartz (Vein Quartz)

Quartz (Silicon Dioxide, SiO2)

Banded Quartz

Silicon Dioxide (SiO2)

Amethyst (Tumbled Quarz)

Silicon Dioxide (SiO2) with iron impurities

Muscovite Mica (Granitic Pegmatite)

Muscovite - KAl2(AlSi3O10)(OH)2

Snowflake Obsidian

Spherulitic Obsidian (primarily SiO2)

Quartz / Common Opal Transition

Silicon Dioxide (SiO2)

Amethyst (Rose-tinted variation)

Silicon Dioxide (SiO2) with trace iron impurities

Smoky Quartz

Silicon Dioxide (SiO2)

Black Obsidian

Obsidian (Volcanic Glass)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Chert (variant Flint/Jasper)

Microcrystalline Opaline Silica (SiO2)

Pumice or Tufa/Travertine

Pumice (if igneous) or Calcareous Tufa (if sedimentary)

Quartz (Druzy)

Silicon Dioxide (SiO2)

Agate (specifically, multi-colored or pastel-dyed agate)

Silicon dioxide (SiO2) - specifically, a cryptocrystalline variety of quartz known as Chalcedony, with banding classified as Agate. (If it were Fluorite, the chemical formula would be Calcium Fluoride - CaF2).

Quartz (Clear Quartz/Rock Crystal)

Silicon Dioxide (SiO2)

Feldspar (Orthoclase)

Orthoclase Feldspar (KAlSi3O8)

Quartz (specifically Clear Quartz or Rock Crystal)

Silicon Dioxide (SiO2)

Slag Glass

Amorphous Silica / Glass Slag

Muscovite Mica (Granitic Pegmatite)

Muscovite - KAl2(AlSi3O10)(OH)2

Black Obsidian

Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)

Quartz (Milky/Chalcedony variety)

Silicon Dioxide (SiO2)

Milky Quartz Pebble

Silicon Dioxide (SiO2)

Quartzite and Jasper Pebbles

Quartzite (re-crystallized Quartz) and Cryptocrystalline Quartz (SiO2)