Iowaite (Size: 1.4 cm x 0.9 cm x 0.2 cm) Locality: Palabora mine (Foscor open pit; PMC mine), Loolekop, Phalaborwa, Limpopo Province, South Africa Original description: Iowaite is a rare Mg-Fe hydroxide of the Hydrotalcite Group. This is a very fine, two-sided compound tabular crystal with high lustre and nicely translucent edges. The world's finest examples of the species come from this large open pit mine. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Iowaite
Iowaite is an IMA-recognized mineral species in the halide class, with the chemical formula Mg₆Fe³⁺₂(OH)₁₆Cl₂·4H₂O.
It crystallizes in the hexagonal crystal system (space group R-3m). It is a member of the Hydrotalcite structural group.
Key properties: Mohs hardness 1.5–2.5; specific gravity 2.09; White streak; Greasy luster; optically uniaxial.
IMA symbol Iow, IMA status: approved, named in 1967.
An alteration product of serpentine.
It is found associated with Chrysotile, dolomite, brucite, calcite, magnesite, pyrite, pyroaurite (Sioux Co., Iowa, USA); magnetite, chondrodite, clinochlore, brucite, hydrotalcite.
The name refers to its occurrence in the state of Iowa, USA.