Bernalite
Bernalite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula Fe(OH)₃.
It crystallizes in the orthorhombic crystal system (space group Immm). It is a member of the Perovskite structural group.
Key properties: Mohs hardness 4; specific gravity 3.32; Apple-green streak; Vitreous to adamantine when fresh; resinous on crystal surfaces luster.
IMA symbol Bnl, IMA status: approved, named in 1991.
On a museum specimen from a metamorphosed Pb-Zn deposit, probably from the surface oxidation zone.
It is found associated with Goethite, coronadite.
The mineral was named to honor John Desmond Bernal (1901-1971), British crystallographer and historian of science.
Index entry. This entry combines official IMA/RRUFF species data with published physical-property data — a full written entry hasn’t been published yet.
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