Industrial Byproduct (Anthropogenic Material)

Sandstone (Pebble / Cobble)

Arenite / Sedimentary Rock (composed of quartz and feldspar)

Quartz (Iron-Stained / Yellow Quartz)

Silicon Dioxide (SiO2)

Thunderegg (Agate or Quartz Geode)

Silica-filled rhyolitic nodule (SiO2)

Sandstone

Arenite

Sandstone

Arenite (SiO2 primarily)

Sandstone

Arenite (SiO2 primarily)

Chert (Flint)

Silicon Dioxide (SiO2)

Sedimentary Sandstone (Sandstone Slab)

Arenite (SiO2 with Fe2O3 staining)

Sandstone

Arenite

Sandstone

Clastic sedimentary rock (primarily SiO2)

Sandstone (with Iron Staining)

Clastic sedimentary rock (primarily Quartz with Limonite/Goethite staining)

Sandstone

Arenite (composed primarily of SiO2)

Chert (often called Flint when found in chalk)

Microcrystalline Quartz (SiO2)

Jasper

Microcrystalline Quartz (SiO2)

Chert / Jasper

Silicon Dioxide (SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Jasper

Silicon Dioxide (SiO2) with impurities

Jasper

Microcrystalline quartz (SiO2)

Petrified Wood

Silicified Wood (SiO2)

Chert (Flint Nodule)

Microcrystalline quartz (SiO2)

Banded Jasper

Silicate Mineral (Microcrystalline Quartz / SiO2)

Limonite (Iron Ore)

FeO(OH)·nH2O

Chert (Flint)

Microcrystalline Quartz (SiO2)

Chalcedony (Agate)

Silicon Dioxide (SiO2)

Shungite

Non-crystalline carbon (allotrope of carbon)

Granite

Phaneritic plutonic igneous rock (SiO2-rich)

Basalt with Weathering Rind

Basalt (Mafic Volcanic Rock)

Pink Granite

Granite (Alkali-feldspar granite)

Quartzite

Quartzite (SiO2)

Bauxite

Bauxite (Al2O3·2H2O)

Pink Granite

Phaneritic Felsic Igneous Rock (Granite)

Quartzite

Quartzite (SiO2)

Pink Quartzite

Quartzite (High-silica metamorphic rock)

Granite

Granite (Felsic Intrusive Igneous Rock)

Granite

Granite (Phaneritic igneous rock)

Quartzite

Quartzite (SiO2)

Anthracite Coal

Anthracite

Banded Gneiss

Gneiss

Limestone

Calcium Carbonate (CaCO3)

Coquina

Bioclastic Limestone

Quartzite

Quartzite (primarily SiO2)

Basalt

Basalt