Plumboferrite, Hausmannite, Dolomite
Jakobsberg Mine, Jakobsberg ore field, Nordmark mining district, Filipstad, Värmland County, Sweden
6.0 x 4.0 x 3.5 cm. An excellent micaceous specimen from the type locality, consisting of elongate, platy, subhedral crystals of gray-black plumboferrite up to 1.5 mm inter-grown with brown-black, fine-grained, granular hausmannite and localized, cream-colored, discontinuous bands of dolomite. Plumboferrite is a lead iron manganese oxide. The ...
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