Sedimentary (Primary) With Artificial Modification

Red Sandstone

Arenite

Ironstone (Limonitic Shale)

Ferruginous Siltstone / Goethite-rich Sedimentary Rock

Chert (Tan/Grey variety)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Chert (often called Flint or Jasper)

Cryptocrystalline quartz (SiO2)

Chert (Flint)

Chert (SiO2)

Chert (Jasper/Flint variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Banded Iron Formation (BIF) / Iron Ore

Hematite-Magnetite BIF (Fe2O3 / Fe3O4 mixed with SiO2)

Bauxite

Bauxite (mixture of hydrous aluminum oxides: Al(OH)3 & AlO(OH))

Bauxite

Bauxite (Al(OH)3, AlO(OH))

Sandstone (Water-worn)

Arenite

Orange Calcite

Calcium Carbonate (CaCO3)

Hematite

Iron(III) oxide (Fe2O3)

Hematite

Iron(III) oxide (Fe2O3)

Limestone

Calcium carbonate (CaCO3)

Limestone

Calcareous sedimentary rock (primarily Calcium Carbonate, CaCO3)

Limestone

Calcium Carbonate (CaCO3)

Sandstone

Arenite (composed primarily of Quartz: SiO2)

Chert (Flint) Nodule

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Limestone

Calcium Carbonate (CaCO3)

Limestone

Calcium Carbonate (CaCO3)

Quartz (Milky or Druzy Quartz)

Silicon Dioxide (SiO2)

Yellow Ochre / Limonite

Hydrated Iron(III) Oxide-Hydroxide (FeO(OH)·nH2O)

Chert (variations include Flint/Jasper)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Commonly known as Flint or River Pebble)

Microcrystalline Quartz (SiO2)

Chert / Yellow Jasper

Silicon Dioxide (SiO2)

Bauxite

Al2O3·2H2O (principally composed of gibbsite, boehmite, and diaspore)

Chert (Field-collected variety)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Sandstone (with Iron Staining)

Clastic sedimentary rock (primarily SiO2 with Fe2O3 oxides)

Onyx (Black Onyx)

Onyx (Silicon Dioxide, SiO2)

Limonite (Iron Ore)

Limonite (Hydrated Iron Oxide, FeO(OH)·nH2O)

Manganese Ore (Psilomelane/Pyrolusite)

Psilomelane ((Ba,H2O)2Mn5O10) and Pyrolusite (MnO2)

Sandstone (Ferruginous)

Arenite with Iron Oxide (Fe2O3) cement

Gossan with Copper Carbonate (Chrysocolla/Malachite)

Ferruginous Oxide (Gossan) with Cu2CO3(OH)2 (Malachite) or (Cu,Al)2H2Si2O5(OH)4 (Chrysocolla)

Optical Calcite (Iceland Spar)

Calcium Carbonate (CaCO3)

Yellow Calcite

Calcium Carbonate (CaCO3)

Chert (White Chert / Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Flint)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Coal (specifically Bituminous or Anthracite)

Organic sedimentary rock; primarily Carbon (C) with varying H, S, O, N

Limonite (Iron Stone Concretion)

Limonite (Hydrous Iron Oxide) - FeO(OH)·nH2O

Bismuth

Bismuth (Bi)

Orange Calcite

Calcite (Calcium Carbonate - CaCO3)

Flint (within Limestone matrix)

Silicon dioxide (SiO2)