Bernalite, Fe(OH)3, a new mineral from Broken Hill, New South Wales: description and structure

Bernalite, a new iron hydroxide mineral from New South Wales, Australia, is a flattened pyramidal or a pseudo-octahedral bottle-green crystal with a vitreous to adamantine luster. An uneven to conchoidal fracture and Mohs hardness of 4 appear in the brittle mineral which has no cleavage. The pseudocubic Bernalite has a crystal structure solved by the Patterson methods, but the effect of polysynthetic twinning prevents full refinement. A three dimensional network of corner-connected octahedra represents the distorted Re O3-like structure. The mineral has been named after the British crystallographer J.D. Bernal.