Mineral And Glass

Milky Quartz Pebble with Iron Inclusions

Silicon Dioxide (SiO2)

Sandstone (Quartz-rich)

Arenite

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Sandstone (with Limonite staining)

Arenite (primarily SiO2 with FeO(OH)·nH2O)

Potassium Feldspar (Orthoclase)

Orthoclase (KAlSi3O8)

Clear Quartz

Silicon Dioxide (SiO2)

Quartz with Iron Oxide Inclusions

Silicon Dioxide (SiO2)

Garden Quartz (Lodalite)

Silicon Dioxide with various mineral inclusions (SiO2)

Quartz

SiO2 (Silicon Dioxide)

Arsenopyrite in Quartz Matrix

Arsenopyrite (FeAsS) with Quartz (SiO2)

Quartz (Grain/Fragment)

Silicon Dioxide (SiO2)

Smoky Quartz

Silicon Dioxide (SiO2)

Obsidian (black volcanic glass)

Obsidian; predominantly rhyolitic volcanic glass, mainly SiO₂ with minor feldspar, quartz, and iron oxides

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Amethyst

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

Slag Glass

Vitreous Silicate Residue

Slag

Ferrous slag (by-product of iron smelting)

Muscovite Mica

KAl2(AlSi3O10)(OH)2

Yellow quartz crystal (likely citrine)

Quartz, silicon dioxide (SiO₂), iron-colored variety commonly called citrine

Milky Quartz

Silicon Dioxide (SiO2)

Quartz Crystal with Inclusions

Silicon Dioxide (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Citrine

Citrine (Silicon Dioxide, SiO2)

Blue Apatite

Fluorapatite (Ca5(PO4)3F)

Fulgurite

Lechatelierite (Silica glass)

Amethyst (likely tumbled or polished)

Quartz, SiO₂; purple color commonly caused by trace iron and natural irradiation

Black Obsidian

Volcanic Glass (SiO2)

Obsidian

Volcanic Glass (SiO2)

Obsidian

Volcanic Glass (SiO2)

Pink Feldspar (Orthoclase)

Orthoclase Feldspar (KAlSi3O8)

Unidentified pale mineral fragment

Likely quartz or calcite; image resolution prevents confident identification

Tumbled pink chalcedony (likely rose quartz or pink agate)

Chalcedony, microcrystalline quartz (SiO₂); exact variety is uncertain from the image

Tumbled pale blue-green quartz (likely aquamarine-bearing quartz)

Quartz, SiO₂; blue coloration may reflect inclusions or minor iron-bearing minerals

Muscovite Mica

Muscovite (KAl2(AlSi3O10)(OH)2)

Pink Granite (Unakite-bearing or Epidote-bearing Granite)

Plutonic Igneous Rock (Granite)

Banded sandstone pebble

Quartz-rich lithic sandstone; exact provenance and composition require testing

Quartz Vein in Sedimentary Rock

Silicon Dioxide (SiO2) with host Chert or Limestone

Obsidian

Obsidian (Volcanic Glass)

Quartz Pebble (with Iron Inclusions)

Silicon Dioxide (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)