Sedimentary (With Some Aspects Of Mineral Replacement)

Tektite (likely Australite)

Tektite (no specific chemical formula as it's a natural glass of variable composition, mostly SiO2, Al2O3, FeO, MgO, CaO, K2O, Na2O, TiO2)

Native Copper (Penny specimen)

Native Copper (Cu)

Pyrite

Iron Sulfide (FeS2)

Limonite (Iron Ore)

Limonite (Iron oxide-hydroxide mixture, FeO(OH)·nH2O)

Magnetite Sand (Black Sand)

Magnetite (Fe3O4)

Granite

Granite (a common term for a felsic intrusive igneous rock)

Sandstone (with Iron Staining)

Clastic sedimentary rock (SiO2 with Fe2O3 oxides)

White Calcite

Calcium Carbonate (CaCO3)

Limonite with Trace Fossils

Hydrous Iron Oxide Mixture (FeO(OH)·nH2O)

Quartz Geode (with possible Manganese or Goethite coating)

Silicon Dioxide (SiO2)

Limonite Concretion

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

Sandstone (Calcareous or Ferruginous)

Clastic sedimentary rock (SiO2 with CaCO3 or Fe2O3 cement)

Limonite Concretion (Ironstone)

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

Turquoise

CuAl6(PO4)4(OH)8·4H2O

Rhodonite

Rhodonite (MnSiO3)

Sandstone (Ferruginous)

Arenite with Iron-Oxide Cement (primarily SiO2 with Fe2O3/FeOOH)

Mixed Tumbled Gemstones (Agate, Aventurine, Pyrite, etc.)

Multiple (principally Silicon Dioxide SiO2 and Iron Disulfide FeS2)

Pyrite in Shale

Iron Disulfide (FeS2)

Banded Onyx (Mexican Onyx / Travertine)

Calcite (CaCO3) - Banded Travertine

Black Tourmaline

Schorl (Na(Fe²⁺)₃Al₆(BO₃)₃Si₆O₁₈(OH)₄)

Shale or Slaty Mudstone

Argillaceous sedimentary rock

Limonite/Goethite on Shale

Hydrous ferric oxides (FeO(OH)·nH2O) often associated with argillaceous rock

Specular Hematite

Hematite (Fe2O3)

Pyrite on Quartz matrix

Iron Disulfide (FeS2) on Silicon Dioxide (SiO2)

Rhodochrosite

Manganese Carbonate (MnCO3)

Blue Apatite

Fluorapatite (Ca5(PO4)3F)

Pebble

Clast (specifically a granule or small pebble)

Sandstone with Secondary Mineral Encrustation

Arenite with Silica/Calcite deposits (SiO2 or CaCO3)

Shale

Shale (Consolidated fine-grained clay/silt)

Halite (Rock Salt)

Halite (Sodium Chloride, NaCl)

Geode (Unopened)

Siliceous Septarian Concretion / Geode (SiO2)

Picture Jasper

Silicon Dioxide (SiO2) with iron oxide and organic impurities

Boxwork Siderite or Sepatarian Nodule Weathering

Siderite (FeCO3) with secondary mineralization or Boxwork Geode fragment

Sandstone

Arenite (SiO2 dominant)

Quartz Geode

Silicon Dioxide (SiO2)

Pyrite (Fool's Gold) Cube

Iron Sulfide (FeS2)

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Yellow Ochre / Limonite

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

Limonite (Ironstone)

Limonite (mixture of hydrated iron oxides, primarily Goethite α-FeO(OH))

Sandstone

Arenite (primarily SiO2)

Septarian Nodule

Septarian Concretion (Calcium Carbonate/Aragonite/Calcite)

Kambaba Jasper

Stromatolite / Fossilized Algae (Rhyolitic structure)