Sedimentary Rock (Technically Chert, A Microcrystalline Quartz)

Quartzite

Quartzite (primarily SiO2)

Chert (Flint nodule)

Chert (SiO2)

Clear Quartz

Silicon Dioxide (SiO2)

Clear Quartz

Quartz (Silicon Dioxide, SiO2)

Petrified Wood

Silicified Wood (primarily Quartz/Chalcedony, formula SiO2)

Chert (Flint)

Silicon Dioxide (SiO2)

Quartz Vein in Host Rock (Breccia/Rhyolite)

Silicon Dioxide (SiO2) with matrix

Chert (variations include Flint or Jasper)

Chert (SiO2)

Clear Quartz

Silicon Dioxide (SiO2)

Grey Chalcedony (Tumbled Moon)

Microcrystalline Quartz (SiO2)

Chalcedony with Druzy Quartz Geode

Silicon Dioxide (SiO2)

Yellow Quartzite (River Stone)

Quartzite (primarily SiO2)

Banded Flint (Chert)

Silicon Dioxide (SiO2)

Chert / Flint

Chert (Silicon Dioxide, SiO2)

Clear Quartz Crystal

Silicon Dioxide (SiO2)

Quartzite Pebble

Metamorphosed Sandstone (SiO2)

Quartz Geode

Silicon Dioxide (SiO2) within a geode

Quartzite Pebble

Metamorphic rock predominantly composed of Quartz (SiO2)

Banded Agate

Microcrystalline Quartz (SiO2) with impurities

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Chert Concretion (with typical hematite/limonite staining)

Sedimentary Concretion (SiO2 with FeO(OH)⋅nH2O)

Milky Quartz Vein in Host Rock

Silicon Dioxide (SiO2)

Jasper (specifically Red Jasper or Iron-stained Chert)

Silicon dioxide (SiO2) with iron oxide inclusions

Quartzite

Quartzite (composed mainly of SiO2)

Banded Iron Formation (BIF)

Banded Iron Formation

Agate (Chalcedony Variation)

Silicon Dioxide (SiO2)

Moss Agate

Silicon dioxide (SiO2) with inclusions of hornblende or chlorite

Chert (specifically Black Chert / Flint)

Silicon Dioxide (SiO2)

Chert (Chert Nodule)

Silicon Dioxide (SiO₂)

Sandstone

Clastic Sedimentary Rock (composed mostly of SiO2)

Clear Quartz (Rock Crystal)

Quartz (Silicon Dioxide, SiO2)

Quartzite

Quartzite (SiO2)

Black Obsidian

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

Ironstone Concretion (likely)

Goethite/Hematite/Limonite cemented sediment

Chert (Basanite / Flint)

Microcrystalline silica (SiO2)

Sandstone

Arenite (SiO2, often with CaCO3 or Fe2O3 cement)

Sandstone Concretion

Sedimentary concretion

Vesicular Basalt with Quartz/Chalcedony

Vesicular Basalt (primarily Plagioclase, Pyroxene, and Olivine with SiO2 infill)

Milky Quartz

Silicon Dioxide (SiO2)

Grey Agate (Tumbled)

Silicon Dioxide (SiO2)

Quartzite (Quartz-rich Cobble)

Quartzite (SiO2)

Chert (Jasper variety)

Chert (Silicon Dioxide, SiO2)