Mineral, Specifically An Iron Ore

Black Tourmaline

Schorl (Sodium Iron Aluminum Borosilicate Hydroxide)

Pyrite Nodule

Iron Sulfide (FeS2)

Citrine

Silicon Dioxide (SiO2) with iron impurities

Hematite (Iron Ore Boulder)

Hematite (Fe2O3)

Chalcopyrite

Copper iron sulfide (CuFeS2)

Gossan (Iron Hat)

Iron oxide-rich weathered rock (primarily Limonite and Goethite with secondary Quartz)

Ferruginous Sandstone

Arenite with Iron-Oxide cement (Fe2O3 · nH2O)

Iron-oxide-bearing rock fragment

Likely limonite/goethite with quartz or host-rock inclusions; exact identification requires testing

Likely weathered metallic mineral or slag fragment

Indeterminate; possibly iron-rich sulfide/oxide material or industrial slag

Botryoidal Goethite on Quartz

Goethite (α-Fe3+O(OH)) on Quartz (SiO2)

Pyrite in Matrix (Fool's Gold)

Iron Disulfide (FeS2)

Citrine Quartz

Silicon Dioxide (SiO2) with iron impurities

Chalcopyrite (Peacock Ore)

Copper Iron Sulfide (CuFeS2)

Red Jasper

Silicon Dioxide (SiO2) with Hematite impurities

Green Calcite

Calcite (Calcium Carbonate, CaCO3)

Picture Jasper

Silicon Dioxide (SiO2) with iron oxide inclusions

Hemimorphite or Red Quartz

SiO2 (Quartz) / Zn4Si2O7(OH)2·H2O (Hemimorphite)

Limonite/goethite-rich ironstone (probable)

Limonite, chiefly hydrated iron oxides; commonly goethite, α-FeO(OH), with possible quartz or host-rock inclusions

Tree Agate

Chalcedony (SiO2) with Dendritic inclusions

Gossan (Limonite/Ironstone)

Hydrated Iron Oxide (FeO(OH)·nH2O)

Yellow Ocher (Limonite)

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

Ironstone Concretion (Nutstone)

Ironstone (with High Limonite/Hematite Content)

Rose Quartz

Silicon Dioxide (SiO2) with trace amounts of titanium, iron, or manganese

Unidentified weathered mineral/rock fragment

Indeterminate; likely a weathered iron-rich silicate or sulfide-bearing specimen

Hematite

Iron(III) oxide (Fe2O3)

Tiffany Stone

Bertrandite Fluorite (CaF2 + Be4Si2O7(OH)2)

Pyrite (or Arsenopyrite / Ore mineral aggregate)

FeS2 (Iron Sulfide)

Hematite

Iron(III) oxide (Fe2O3)

Rose Quartz

Silicon dioxide with traces of titanium, iron, or manganese (SiO2)

Sandstone with Iron Staining

Clastic sedimentary rock (primarily SiO2 with Fe2O3)

Polished Hematite Tower

Hematite (Fe2O3)

Specular Hematite

Specularite (Fe2O3)

Hematite Pebble

Hematite (Alpha Fe2O3)

Magnetite-rich iron ore

Magnetite (Fe₃O₄), possibly with hematite and silicate matrix

Tumbled Hematite

Iron(III) oxide (Fe2O3)

Magnetite with Pyrite or Chalcopyrite inclusions

Magnetite (Fe3O4) with Pyrite (FeS2)

Magnetite (potentially Hematite)

Magnetite (Fe₃O₄)

Yellow Ochre / Limonite

Limonite (FeO(OH)·nH2O)

Limonite (Iron Stone/Iron Ore)

FeO(OH)·nH2O (Hydrous ferric oxide)

Orange Calcite

Calcium Carbonate (CaCO3)

Orange Calcite

Calcium Carbonate (CaCO3)

Orange Calcite (Carved as a Horned Skull)

Calcium Carbonate (CaCO3)