1006 The American Naturalist. [November, 
tals measure 30-50 mms. across. They are almandine-red in color, 
are translucent, and have a light pink streak, a hardness of 5.5 and a 
density of 3.350. An analysis gave : 
SiO, FeQ MnO ZnO BeO CaO S Total 
29.48 37.53 11.28 487 1417 tr 5.04=102.62 
corresponding to R.S. 7RO. 38iO,. 
Mirabilite Changed to Thenardite.—Two crystals of mirabil- 
ite implanted on a mass of rock-salt from Aussee, Salzkammergut, that 
has been in the possession of the University of Vienna six years, have, in 
this time, so changed that they now consist simply of a thin shell com- 
posed of a crystalline aggregate whose inner surface is completely 
drusy. Within this crust there is usually a hollow, but occasionally a 
part of the hollow may be filled by a group of crystals like those form- 
ing the shell. These crystals are determined by Pelikan" to be then- 
ardites of a short pyramidal habit, bounded by the planes P. 4P, Px, 
3Px and oPx, with an axial ratio of a: b: c == .5970 : 1 : 1.2541. The 
crystals had been kept during the six years in an air-tight enclosure at 
a nearly uniform temperature, so that the change from their original 
condition must have been due solely to the influence of the small 
amount of moisture within the enclosure. 
Mineralogical News.—Crystals of the rare uranatile from 
Schneeberg, Saxony, and from the Joachimsthal, Bohemia, have been 
measured by Pjatnitzky,” who concludes that they are triclinic and not 
orthorhombic as Zepharovich supposed. Their axial ratio a: b : c= 
-6257 :1:.5943. The mineral has a citron or sulphur-yellow color, 
with very weak dichroism. Uranophane, according to the author, 
should not yet be considered a species. Its chemical composition is 
the same as that of uranatile, but its crystallization has not yet been 
determined. 
The rare plane 2020 has been detected by Pelikan" on salt crystals 
from Stannia, Galicia. Upon examining sections of halite from this 
locality, the author discovered in them many inclusions of petroleum 
zonally arranged. The cavities in which the oil is contained are either 
pear-shaped or are negative crystals, entirely or only partially filled 
with the liquid, which must have been under greater pressure at the 
14 Min. u. Petrog, Mitth., 1892, ied 476. 
55 Zeits. f. Kryst., xxi, 1892, p. 74. 
16 Min. u. Petrog Mitth., xii, p. wm 
