Tektite (Natural Glass)

Yellow Jasper

Silicon Dioxide (SiO2) with iron oxide inclusions

Jasper (Red Jasper)

Silicon Dioxide (SiO₂)

Red Jasper

Silicon Dioxide with Iron Oxide impurities (SiO2 + Fe2O3)

Red Jasper

Silicon Dioxide with Hematite inclusions (SiO2 + Fe2O3)

Pyrite

Iron Disulfide (FeS2)

Red Jasper

SiO2 (Silicon Dioxide with Iron inclusions)

Small quartz-rich pebble

Quartz (SiO₂), possibly quartzite or weathered granite fragment

Tumbled tan pebble, likely sandstone or chert

Uncertain; probable quartz-rich sandstone (SiO₂-bearing)

Orange chalcedony or weathered quartz pebble

Microcrystalline quartz, SiO₂; possibly iron-oxide-stained chalcedony

Quartz Pebble

Silicon Dioxide (SiO2)

Amethyst

Quartz (Silicon Dioxide with iron impurities), SiO2

Amethyst

Silicon dioxide with iron impurities (SiO2 + Fe3+)

Amethyst

SiO2 (Silicon Dioxide with Iron impurities and irradiation)

Amethyst (vibrant lilac/purple variety)

Silicon Dioxide (SiO2) with iron impurities

Amethyst

SiO2 (Silicon Dioxide) with Iron (Fe3+) impurities

Amethyst

Amethyst (Silicon Dioxide, SiO2 + Fe4+ impurities)

Amethyst quartz crystal cluster

Quartz, SiO₂; purple coloration from irradiation and trace iron

Pegmatitic granite (likely feldspar–quartz–mica rock)

Granitic pegmatite; chiefly K-feldspar and quartz, with mica and iron-oxide staining

Moonstone (Feldspar)

Orthoclase (KAlSi3O8) or Albite (NaAlSi3O8)

Quartz (Milky Quartz/Citrine Type)

Silicon Dioxide (SiO2)

Granite

Granite (a plutonic igneous rock composed primarily of quartz, feldspar, and mica)

Black Onyx

Chalcedony (Silicon Dioxide - SiO2)

Quartz-bearing granite or gneiss fragment

Granite/gneiss composed mainly of quartz (SiO₂), feldspar, and minor mica or ferromagnesian minerals

Rounded granitic gneiss or granite cobble

Granite; primarily quartz, plagioclase and potassium feldspar with biotite/hornblende

Lepidolite

Lepidolite (K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2)

Tumbled amethyst

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

Black Onyx

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Fine-grained gray sandstone or quartz-rich sedimentary pebble

Likely quartz arenite or lithic sandstone; exact identification requires microscopy or testing

Quartz pebble

Silicon Dioxide (SiO2)

Weathered quartz-rich pebble (tentative)

Likely quartz/chalcedony, SiO₂, possibly iron-stained

Tumbled quartz-rich pebble, possibly quartzite

Quartzite (mostly SiO₂), or quartz-bearing chert; exact identification requires testing

Quartz Veined Basalt Pebble

Amygdaloidal Basalt with Quartz (SiO2) veining

Herkimer Diamond

Quartz (Silicon Dioxide, SiO2)

Polished Agate (Yellow/Grey Agate Pendant)

Silicon Dioxide (SiO2)

Dyed Quartz (often sold as 'Blue Quartz' or 'Blue Agate')

Silicon Dioxide (SiO2) with artificial pigment

Herkimer Diamond

Quartz (Silicon Dioxide) - SiO2

Smoky Quartz

Silicon Dioxide (SiO2)

Emerald

Beryl (Be3Al2(SiO3)6) with trace Chromium/Vanadium

Green Quartz (Prasiolite)

Crystalline Silicon Dioxide (SiO2)

Blue Sapphire (faceted in jewelry)

Corundum (Al2O3)

Blue Topaz

Aluminum silicate fluoride hydroxide [Al2SiO4(F,OH)2]

Citrine Geode Fragment

Silicon Dioxide (SiO2) with iron impurities