METALLIFEROUS MINERALS. 223 CRONSTEDTITE* Ithombohedral Melane Mica, M. Cronstedit, L. Sideroschisolite. Contains Oxide of iron 58-85 Silica 22-45 Oxide of manganese 2-89 Magnesia 5-08 Water 10-70—Steinmann. Sp. Gr. 3-3—3-35. H. = 2-5. Massive and crystallized; the massive consisting of black and opake fibres, having a brilliantlustre; the crystallized occasionally in separate six-sided prisms, more often however the prisms ad here laterally. In thin laminse, somewhat elastic; streak dark leek-green ; cleavage distinct perpendicular to the axis. Before the blowpipe it intumesces slightly, but does not melt. With borax it affords with difficulty a hard, black, and opake enamel. When reduced to powder it gelatinizes in concentrated muriatic acid. It is found near Przibram in Bohemia with carbonate of iron ; in diverging groups at Wheal Maudlin in Cornwall; and asso ciated with quartz and magnetic pyrites at the mines of Congho- nas do Campo in Brazil. PINGUITE. Leonhard. '• -V’f/ ■ p Y Contains oxide of iron 35-60, silica 36 90, alumina 1-80, mag nesia 0-45, oxide of manganese 0-14, water 25-10—Kersten. Sp. Gr. 2-315. II. under 2-0. Pinguite occurs in masses of a siskin- or oil-green colour ; with a slightly resinous lustre; and conchoidal or uneven fracture; feels greasy ; does not adhere to the tongue, and emits a feeble argillaceous odour when struck. Streak lighter than the mineral. Extremely soft, resembling newly made soap. In the matrass it yields much water. Before the blowpipe per se it becomes black, but only fuses on the edges. With bo rax it melts easily, exhibiting the presence of iron ; as also with salt of phosphorus, in which a skeleton of silica remains. Occurs in a vein of barytes at Wolkenstein in the Erzgebirge, and has been severally described by Breithaupt, l'reisleben, and Beckmann. • In honour of Cronstedt, the Swedish mineralogist.