ALUNITE. 539 Prismatic. a 100, c 001, m 110. no. 534. ac me ma mm! 90 o' 90 0 67 30 66 0 Combinations, acm. Cleavage, m, imper fect. Fracture uneven. Translucent. Lustre waxy, in the fibrous varieties silky. Red. of various shades. Streak white. Rather brittle, n = 3'6. g = 2'73.. .2'78. Taste bitter and saline, feeble. In the matrass yields water. Before the blowpipe on charcoal melts readily into an opaque reddish bead, which, on cooling, becomes white and alkaline.. Partially soluble in water leaving a residue of sulphate of lime. KS + MgS + sC.8 -I all, sulphate oflime45'2, sulphate of magnesia 20 - l, sulphate of potash 28 - 8, water 6'9. Analyses of polyhalite from Ischel a by Stromeyer, from Aussee b by Rammelsberg:— Sulphate of lime . . . Sulphate of magnesia . Sulphate of potash . . Chloride of sodium . . Chloride of magnesium Water Red oxide of iron . . Silica a 44'74 20-03 27-70 o-ie O'Ol 6-95 0-34 46'43 20-59 28-10 o-ii 5-24 0-33 0'20 Is found with rock salt, in crystals, fibrous and compact masses, and pseudomorphous after rock salt, at Aussee in Stiria, Ischel in Austria, and Berchtesgaden in Bavaria. 370. ALUNITE.— Alum-stono; Phillips. Alunite ; Beu- dant. Rhomboedrisches Alaun-IIaloid; Mohs. Alaunstein; Hausmann. Alunit; Haidinger. Rhombohedral. 100,111 = 52° 45 f . o ill, r 100. A a 6
