- Syn. Schwarzer Braunstein, Werner. Foliated Black Manganese-Ore, Jameson, ed. 3, v. III, p. 236.
The principal characters that distinguish this rare ore of Manganese, arc its dark colour, close texture, and the acute pyramidal form of its crystals; generally the crystals are so closely aggregated together as to form a solid mass, in which they are only distinguished by their foliated structure, their external form is seen where they occur upon the surfaces of hollows. The mass has much the appearance of an opaque Iron Slag, but of a purpler black colour. The fracture of the compact parts is even with a dull surface, but the crystals having a foliated structure, give a ragged shining fracture. The powder is of the same colour as the mass. It is heavier than most other ores of Manganese. Although a foliated structure is very manifest yet it is difficult to obtain regular cleavages, but I think I have succeeded in procuring several inclined upon the faces of the acute octohedron, so as to give a more obtuse octohedron for the primitive; faces parallel to this exist around the truncated apices of several crystals upon the specimen figured. Jameson says, this mineral occurs in vein in secondary Porphyry, in the Manganese formation o.
Oehrenstok near Ilmenau in Thuringia, my specimen is said to be from Elgersburg near Gotha, and is accompanied by purple Fluor.
Berzelius speaks of an ore of Manganese crystallized in octahedrons, which he says comes from Piedmont, he gives the following analysis.
|Brown oxide of Manganese||75.80|
|Oxide of Iron||4.14|
Whether this be the same kind of ore as the one before as, I cannot say his description is so short, it agrees however in not being altered before the blow-pipe except externally.