Sedimentary (Cryptocrystalline Quartz)

Siltstone

Siltstone (primarily SiO2, Al2O3)

Sandstone

Arenite (SiO2, often with CaCO3 or Fe2O3 cement)

Sandstone (Quartzose)

Arenite (SiO2 based)

Mexican Crazy Lace Agate

Silicon Dioxide (SiO2) with iron and aluminum inclusions

Yellow Calcite

Calcite (Calcium Carbonate, CaCO3)

Shale or Slate with Quartz Veins

Shale (fine-grained clastic sedimentary rock) or Slate (low-grade metamorphic rock formed from shale) with Quartz (SiO2) veins

Quartz (Milky/Common)

Silicon Dioxide (SiO2)

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Yellow Calcite

Calcium Carbonate (CaCO3)

Quartz Pebble

Silicon Dioxide (SiO2)

Clear Quartz

Quartz (Silicon Dioxide, SiO2)

Jasper with Quartz inclusion

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Brown Sandstone

Arenite (primarily Quartz and Feldspar, with Iron Oxide cement)

Quartz (Milky or Smoky Quartz)

Silicon Dioxide (SiO2)

Quartz (Common Milky Quartz)

Silicon Dioxide (SiO2)

Milky Quartz (Vein Quartz)

Silicon Dioxide (SiO2)

Tree Agate

Dendritic Agate (Silicon Dioxide, SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Clear Quartz Crystal

Silicon Dioxide (SiO2)

Sandstone with Iron Concretion

Arenite with Limonite/Goethite Concretion

Red Jasper (Polished)

Silicon Dioxide (SiO2) with Hematite inclusions

Sandstone

Arenite (composed primarily of SiO2)

Zebra Jasper

Silicon Dioxide (SiO2) with various inclusions

Sandstone (Ferruginous)

Arenite (primarily SiO2 with Fe2O3 staining)

Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Quartz (Druzy)

Silicon Dioxide (SiO2)

Sandstone

Arenite (SiO2 primarily)

Sandstone (likely Arkose)

Arenite (composed mainly of SiO2 with Feldspar)

Sandstone (Yellow/Tan Sandstone)

Arenite (primarily Quartz, SiO2)

Clear Quartz

Silicon Dioxide (SiO2)

Druzy Quartz Geode (likely Smokey Quartz variety)

Silicon Dioxide (SiO2) - specifically a geode formation lined with druzy quartz crystals, with a likely brownish hue indicating smokey quartz.

Ferruginous Sandstone

Sandstone with Iron Oxide (Limonite/Goethite)

Calcite (Iceland Spar)

Calcite (Calcium Carbonate, CaCO3)

Sandstone (Quartzose)

Arenite (primarily SiO2)

Sandstone

Clastic Sedimentary Rock (composed of SiO2 grains)

Sandstone

Arenite (composed primarily of SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Sandstone

Arenite (SiO2 primarily)

Quartz Druse (on Chalcedony/Agate base)

Silicon Dioxide (SiO2)

Petrified Wood

Silicified wood (Quartz/Chalcedony - SiO2)

Carnelian (Agate)

SiO2 (Silicon Dioxide with Iron Oxide impurities)

Clear Quartz

Silicon Dioxide (SiO2)