Igneous, Metamorphic, Sedimentary

Quartz with Matrix

Silicon Dioxide (SiO2)

Tumbled Quartz

Silicon Dioxide (SiO2)

Agate

Silicon Dioxide (Chalcedony), SiO2

Common Opal

Hydrated amorphous silica (SiO2·nH2O)

Blue Quartz

Silicon Dioxide (SiO2) with inclusions

Pyrite

Iron Sulfide (FeS2)

Quartz (Small Fragment)

Silicon Dioxide (SiO2)

Quartz-bearing granite or pegmatite fragment

Likely granitic material composed mainly of quartz (SiO₂), feldspar, and possibly biotite or hornblende

Quartz Crystal

Silicon Dioxide (SiO2)

Pyrite in Matrix

Iron Sulfide (FeS2)

Magnetite (Iron Ore)

Magnetite (Fe3O4)

Pyrite

Iron Sulfide (FeS2)

Quartz pebble

Silicon dioxide (SiO2)

Magnetite (Lodestone)

Magnetite (Fe3O4)

Pyrite

Iron Sulfide (FeS2)

Quartz

Silicon Dioxide (SiO2)

Banded gneiss (likely garnet-biotite or quartz-feldspar gneiss)

Gneiss; predominantly quartz (SiO₂), feldspar, and dark biotite/amphibole

Likely rough quartz with iron-oxide staining

Quartz (SiO₂), possibly with iron-oxide inclusions or surface staining

Milky Quartz

Silicon Dioxide (SiO2)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Quartz (Smoky/Milky variety)

Silicon Dioxide (SiO2)

Magnetite (Iron Ore)

Magnetite (Fe3O4)

Gneiss

Metamorphic Gneiss

Pyrite

Iron Sulfide (FeS2)

Gneiss

Metamorphic Gneiss

Gneiss

Metamorphic Gneiss

Quartz

Silicon Dioxide (SiO2)

Quartz

Silicon Dioxide (SiO2)

Quartz Crystal

Silicon Dioxide (SiO2)

Quartz

Silicon Dioxide (SiO2)

Quartz

Silicon Dioxide (SiO2)

Quartz

Silicon Dioxide (SiO2)

Quartz

Silicon Dioxide (SiO2)

Mica

Phyllosilicate group (e.g., Biotite or Muscovite)

Quartz

Silicon Dioxide (SiO2)

Quartz

Silicon Dioxide (SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Quartz

Silicon Dioxide (SiO2)

Quartz pebble

Silicon dioxide (SiO2)

White Quartz

Silicon Dioxide (SiO2)

Feldspar

Aluminosilicate (KAlSi3O8 - NaAlSi3O8 - CaAl2Si2O8)

Citrine

Silicon dioxide (Quartz variety), SiO2