Mineral	Formula	Crystal System	Occurrences and properties
Graphite	C	Hexagonal	Metamorphic rocks
Sulfur	S	Orthorhombic	Volcanic Precipitate, and in some sedimentary rocks
Native Copper	Cu	Cubic	With other Cu ores - formed via reduction reactions
Hematite	Fe2O3	Hexagonal	Sedimentary iron ores/banded iron formations
Magnetite	Fe3O4	Cubic	Common in igneous and metamorphic rocks/banded iron formations
Ilmenite	FeTiO3	Hexagonal	Minor mineral in mafic igneous rocks
Rutile	TiO2	Tetragonal	Minor mineral in mafic igneous and metamorphic rocks -very high luster
Corundum	Al2O3	Hexagonal	Aluminum-rich metamorphic rocks
Chromite	FeCr2O3	Cubic	Minor mineral in ultramafic igneous rocks - occurs with pink chlorite Kammererite
Goethite	FeO•OH	Orthorhombic	Weathered iron ores; may develop in lateritic soils.
Boehmite	AlO•OH	Orthorhombic	Primary constituent of Bauxite Al ore; forms in lateritic tropical soil horizons