Sedimentary (Chemically Precipitated) Or Metamorphic

Bauxite (Laterite Clay)

Bauxite (mixture of Hydrous Aluminum Oxides: Gibbsite Al(OH)3, Boehmite and Diaspore AlO(OH))

Coal (likely Anthracite)

Anthracite coal

Sandstone with Liesegang Rings

Arenite with secondary Iron oxide (Limonite/Goethite) precipitation

Limestone (specifically Bituminous or Carbonaceous Limestone)

Calcium Carbonate (CaCO3) with Organic Impurities

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Pink Stained Rock (Likely Quartzite or Sandstone with Iron Oxide Staining)

Quartzite (metamorphic) or Sandstone (sedimentary); coloration likely due to hematite or other iron oxides.

Yellow Calcite

Calcium Carbonate (CaCO3)

Quartzite (Water-worn Cobble)

Quartzite (Composition: 90%+ SiO2)

Quartzite (River Pebble)

Metamorphosed sandstone (SiO2)

Limestone (specifically Marl or Chalk)

Calcium Carbonate (CaCO3)

Slate

Foliated Metamorphic Rock (Mainly composed of Quartz, Illite, Chlorite)

Banded Iron Formation (Red Jasper and Hematite Chert)

Banded Iron Formation (BIF); Fe2O3 (Hematite) + SiO2 (Quartz/Jasper)

Ruby in Kyanite

Corundum in Disthene (Al2SiO5 + Al2O3)

Garnet Schist

Almandine Garnet in Mica Schist (Fe3Al2(SiO4)3)

Yellow Howlite (Dyed Magnesite/Howlite)

Dyed Ca2B5SiO9(OH)5 (Howlite) or MgCO3 (Magnesite)

Chert (Flint)

Microcrystalline silica (SiO2)

Coal (specifically Bituminous or Anthracite)

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

Bauxite

Bauxite (Al2O3·2H2O)

Orange Calcite point

Calcite (Calcium Carbonate, CaCO3)

Pyrite

Iron Sulfide (FeS2)

Chert

Chert (Microcrystalline Quartz, SiO2)

Chert (and Chalcedony)

Silicon Dioxide (SiO2)

Banded Chert (River Pebble)

Microcrystalline Quartz (SiO2)

Banded Chert

Silicon Dioxide (SiO2)

Bauxite

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

Chert (Jasper variation)

Microcrystalline Quartz (SiO2)

Orange Calcite

Calcium Carbonate (CaCO3)

Hypersthene

Hypersthene ((Mg,Fe)SiO3)

Diabase

Diabase (also known as Dolerite)

Kidney Stone (Renal Calculus)

Calcium oxalate monohydrate (Whewellite) / CaC2O4·H2O

Chert (Jasper variation)

Silicon dioxide (SiO2)

Chert (Jasper variety)

Silicon Dioxide (SiO2)

Red Garnet

Almandine and Pyrope (Silicate minerals: Fe3Al2(SiO4)3 and Mg3Al2(SiO4)3)

Limestone

Sedimentary Calcite (CaCO3)

Blue Quartz with Dumortierite/Magnesio-riebeckite inclusions

Quartz (SiO2) containing Dumortierite (Al7(BO3)(SiO4)3O3)

Chert (Flint variety)

Chert (SiO2)

Fossilized Coral (Coquina/Limestone)

Cnidaria Anthozoa (Fossilized)

Ironstone (likely Limonite or Goethite)

Ferruginous sedimentary rock (FeO(OH)·nH2O)

Chert (specifically Flint or Jasper variant)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Banded Calcite (often sold as Caribbean Calcite or Pink Calcite)

Calcium Carbonate (CaCO3)

Ferruginous Chert

Silicon dioxide with iron oxide impurities (SiO2 + Fe2O3)

Chert (Chalcedony/Jasper)

Microcrystalline Quartz (SiO2)