1890.] Mineralogy and Petrography. 669 
sist of plagioclase, augite, apatite and secondary substances, and occur 
with the typical structure of granular and aphanitic diabases. They 
are characterized by the zeolitization of the plagioclase. Among the 
zeolites formed are natrolite and analcite, of which the latter has been 
separated and identified by chemical means. —— Thin veins of diabase 
with tachylite borders have produced fusion along the edges of the 
slates through which they cut. According to Rutley? the glassy rim 
produced by the fusion is darker in color than the tachylite selvages of 
the dyke rock. N. H. and H. V. Winchell ® propose a new theory 
for the origin of the iron ores of Minnesota, in opposition to the iron ` 
carbonate theory? of Irving. The new theory follows the same lines 
as does Hunt's crenitic hypothesis. It is based entirely on theoretical 
suppositions, which, so far as is known, can have little foundation in 
facts. 
Mineralogical News.—Aare Minerals.—In an article on the 
minerals of Fiskernäs, in Greenland, Ussing® has given the crystallo- 
graphic and optical properties of several rare minerals. Sapphirine 
has for its axial ratio a: 6: ¢==.65: 1: .93. f5—79? 30°. The axis 
of least elasticity is inclined 8° 30’ to the vertical axis, and 2Vna = 
68° The indices of refraction are a — 1.7055, /$—1.7088, y = 
1.7112. The mineral is negative, and is pleochroic with A colorless, 
and B and C= blue, or 4 = light greenish blue, 3 — dark bluish 
green, and C — yellowish sap green. An analysis of the mineral 
yielded : 
Emo. “ALO, FeO, FeO MgO Los 
12.83 65.29 -93 .65 10.75. .3% 
Kornerupine is orthorhombic with a: ? — .854: 1. It has a specific 
gravity of 3.273, is colorless in ‚thin section, and has ec P& as the 
plane of its optical axes, with c the acute bisectrix, which is negative. 
The optical properties of gedrite and pargasite are also investigated. In 
a few general remarks on the properties of the former mineral the 
author states that it is more probable that the optical angle of the 
orthorhombic hornblendes increases with the increase in the percentage 
of silica rather than with the increase of iron. Atelesite, analyzed 
by Busz,? yielded : 
As,O; Bi,O, Feo, H,O 
14.12 82.41 .51 1.92 
5 Quart. Jour. Geol. Soc., 1889, p. 626. 
8 Zeits. f. Kryst., 1889, XV., p. 596. 
9 Zeits. f. Kryst., 1889, XV., p. 625. 
