Not A Rock (Synthetic Material)

Sandstone (Ferruginous)

Arenite (primarily SiO2 with Fe2O3 staining)

Sandstone with Iron Staining

Arenite (SiO2 based with Fe2O3 staining)

Possible flint or slag fragment

Microcrystalline quartz (chalcedony), or iron-rich industrial slag

Milky Quartz

Silicon Dioxide (SiO2)

Sandstone

Arenite (primarily SiO2)

Sandstone

Arenite (primarily SiO2)

Sandstone

Arenite (primarily SiO2)

Rounded dark river pebble

Likely fine-grained basalt or andesite; exact identification requires a fresh surface or tests

Graphite-veined Quartzite

Meta-sedimentary Quartzite with Carbonaceous/Graphitic Inclusions (SiO2 + C)

Granite Pebble

Granite

Vuggy Chert / Silicified Limestone

Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3) inclusions

Banded Sandstone

Arenite (composed primarily of Quartz: SiO2)

Banded Siltstone

Siltstone (primarily SiO2 with Al2O3)

Red Sandstone

Arenite (primarily Quartz SiO2 with Hematite Fe2O3 cement)

Likely pale limestone or calcite-rich rock

Calcite-bearing limestone; chiefly calcium carbonate (CaCO₃)

Basalt

Basalt (Volcanic Mafic Rock)

Quartz Grain

Silicon Dioxide (SiO2)

Chert (Jasper) Pebble

Microcrystalline Quartz (SiO2)

Chert (Iron-stained)

Microcrystalline Quartz (SiO2)

Polished yellow jasper or opaque chalcedony bead

Microcrystalline quartz (SiO₂), likely iron-oxide-stained jasper

Sandstone with Iron Weathering

Quartz Arenite / Weathered Sandstone

Weathered granitic rock

Granitoid, likely biotite granite or granodiorite

Chert (Flint/Jasper variety)

Silicon Dioxide (SiO2)

Biotite Schist

Biotite Mica Schist (K(Mg,Fe)3AlSi3O10(OH,F)2)

Yellow Ocher (Iron-rich Silt/Clay)

Goethite-rich Limonite (FeO(OH)qnH2O)

Sandstone Pebble

Arenite (SiO2 dominated)

Conglomeratic breccia

Clast-supported polymictic conglomerate/breccia, cemented by silica- or carbonate-rich matrix

Agate

Silicon Dioxide (Chalcedony), SiO2

Chert (Flint Nodules)

Cryptocrystalline Quartz (SiO2)

Rounded granite pebble

Granite, predominantly quartz, feldspar, and mica

Quartz Pebble

Silicon Dioxide (SiO2) with host rock matrix

Chert (variations include Flint or Jasper)

Silicon Dioxide (SiO2)

Red Sandstone

Arenite (SiO2 with Fe2O3)

Chert (Yellow Jasper/Flint)

Microcrystalline Quartz (SiO2)

Ferruginous Sandstone (Ironstone Conglomerate fragments)

Ferruginous clastic sedimentary rock (SiO2 cemented by Fe2O3)

Tumbled orange chalcedony (likely carnelian)

Microcrystalline quartz, SiO₂; iron-bearing variety commonly termed carnelian

Likely weathered sandstone or iron-stained sedimentary fragment

Quartz-rich sandstone; exact identification requires testing

Quartzite with Iron Inclusions

Quartzite (SiO2 with Fe2O3 impurities)

Sandstone

Arenite (primarily SiO2)

Iron Slag (Industrial Byproduct)

Anthropogenic Vitrification Product/Ferrous Slag

Quartzite

Quartzite (SiO2-rich metamorphic rock)

Quartz Pebble

Silicon Dioxide (SiO2)