Metamorphic Or Sedimentary (With Staining)

Sandstone (Ferruginous)

Arenite (composed primarily of SiO2 with iron oxide Fe2O3 cement)

Limonitic Sandstone with Inclusion

Limonitic Quartz Sandstone (primarily SiO2 with FeO(OH)·nH2O)

Chert (Iron-Stained)

Silicon Dioxide (SiO2)

Chert (Iron-stained)

Microcrystalline Quartz (SiO2)

Anthracite Coal

Anthracite (Carbon-rich mineraloid)

Chert (Pebble)

Microcrystalline silica (SiO2)

Quartz (River Pebble)

Quartz (Silicon Dioxide, SiO2)

Sandstone (Quartzose)

Arenite (primarily SiO2)

Limonite and Goethite

Limonite (hydrated iron(III) oxide-hydroxide) and Goethite (α-FeO(OH))

Quartz (Rock Crystal) with minor impurities

Quartz (SiO2)

Sandstone (Green/Yellow Siltstone variant)

Arenite or Siltstone (primarily SiO2 with mineral staining)

Limestone (specifically Travertine or Tufa)

Calcium Carbonate (CaCO3)

Quartzite

Quartzite (Primary mineral: Silicon Dioxide, SiO2)

Bivalve Fossil (Internal Mold)

Class Bivalvia (Phylum Mollusca)

Chert (Yellow Jasper/Flint)

Silicon Dioxide (SiO2)

Chert (Field Stone)

Chert (Silicon Dioxide, SiO2)

Lake Superior Agate

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Chert (Iron-stained)

Silicon Dioxide (SiO2)

Glauconitic Sandstone

Greensand (Glauconite-bearing sandstone)

Spondylus Oyster Calcification / Fossilized Oyster

Spondylus (Thorny Oyster) / Calcium Carbonate (CaCO3)

Chert / Quartz Pebble

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Chert (with Limonite staining)

Microcrystalline Quartz (SiO2)

Sandstone (Ferruginous)

Sandstone (mainly SiO2 with Fe2O3 staining)

Chert (Iron-stained)

Microcrystalline Quartz (SiO2)

Quartz Druze on Matrix

Silicon Dioxide (SiO2)

Chert (with Quartz/Chalcedony)

Microcrystalline Quartz (SiO2)

Chert (Iron-stained)

Chert (primarily Microcrystalline Quartz, SiO2)

Bauxite / Iron-rich Laterite

Laterite (principally Al(OH)3, Fe2O3, and SiO2)

Chert (containing Iron Oxide)

Microcrystalline Quartz (SiO2)

Chert (Flint)

Microcrystalline Opaline Silica (SiO2)

Ferruginous Sandstone (Ironstone)

Clastic sedimentary rock (SiO2 with Fe2O3/FeO(OH) cement)

Blue Calcite

Calcium Carbonate (CaCO3)

Sandstone (Ferruginous)

Arenite (primarily SiO2 with iron oxide cement)

Chert (varietal Flint)

Silicon Dioxide (SiO2)

Sandstone

Arenite (primarily SiO2 with iron oxide cementation)

Oolitic Limestone

Oolite (Sedimentary rock composed of CaCO3)

Sandstone (with Iron Staining)

Clastic sedimentary rock (primarily SiO2)

Banded Chert

Silicon Dioxide (SiO2)

Chert (Iron-stained)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Muscovite Mica

Muscovite (KAl2(AlSi3O10)(OH)2)

Sandstone (Ferruginous)

Arenite (with iron oxide cement, Fe2O3)

Sandstone (Ferruginous)

Arenite (primarily SiO2 with Fe2O3 staining)