1891.] : Mineralogy and Petrography. 373 
examined are 3P, 4P, 2P, œP, Poo, Poo, }P$, 3P$, œP2, and œ P3, 
making ninety-seven forms now known to occur in the species. —— 
Baumhauer*! has discovered some small but good crystals of cryo/if in 
a hand specimen from Evigtok, Greenland, so twinned that both 
individuals have their basal planes in common, and one appears to 
have been revolved about 88° 2’ around an axis normal to the base, 
The limestone of Villefranque and of Biarritz, France, contains 
long needles of quartz and crystals of dipyr and albite,™ the first of 
which must have been formed contemporaneously with the limestone, 
while the last two were produced by the influence of an intrusive mass 
of diabase upon the enclosing rock. Traube * ascribes the differ- 
ences in the values of the axial ratios of different sheedites to the 
amounts of molybdenum occurring in them, Analyses of many 
specimens reveal the fact that white and light yellow varities contain 
but little of this element, while the dark varieties contain quite large 
amounts, (I-8%). The axial ratio of the purest scheelite is 1 : 1.5315, 
that of calcium molybdenate is 1: 1.5458, and that of most scheelites 
between these limits. In the pegmatite veins cutting granite near 
Meissen, Saxony, Sauer and Ussing* have found Baveno twins of 
microcline in which the gridiron structure is lacking. Lamelle of 
albite are intergrown with the microcline, but sufficiently large areas 
of the latter mineral were found to allow of careful measurements of 
cleavage, angles, etc. The angle between the cleavage lines is 89° 30’, 
d the refractive indices for sodium light a= 1.5224, P = 1.5264, 
¥= 1.5295. The optical angle is 2V= 83° 41’. A pure white 
zinc sulphide is mentioned by Mr. Robertson® as occurring at Galena, 
Cherokee Co., Kansas. It is associated with sphalerite, and is in a 
form suggesting the moist, freshly prepared substance. It is saturated 
with water bearing a trace of sulphuric acid. Its composition is: 
Zn = 63.70; S==30.77; Fe,O,= 2.40; Insol.= 2.52. inne * 
gives some good illustrations of micreciine structure in the feldspar of 
the Stockholm granite and of the Kyffhäuser gneiss, and suggests 
reasons for regarding it as a secondary phenomenon produced in non- 
Striated feldspar. The phenacite reported by Mr. Yeates” from 
21 Ib., XVIII., 1890, p. 355. : 
™ Beaugey. Bull. Soc. Franc, d. Min., XIII., Feb., 1890, p. 59. 
33 Neues Jahrb. f. Min., etc., B. B. VIL., p. 232. 
* Zeits. f. Kryst., XVIII., 1890, p. 192. 
3 Amer. Jour. Sci., Aug., 1890, p. 161. 
2 Neues. Jahrb. f. Min., etc., 1890, IL., p. 66. 
7 Amer. Jour. Sci., Sep., 1890, p. 259. 
