1894.] ; Mineralogy and Petrography. 171 
gems. The descriptions are clear but very brief and the illustrations 
in the text are well selected. The little volume is one of the best of its 
kind, though this is but scant praise. 
Gregory’s translation” of Loewinson-Lessing’s Tables for the Deter- 
mination of Rock-Forming Minerals, adds another to the number of 
books thut are supposed to aid the student in the rapid determination 
of the most common constituents of rocks. The tables are intended to 
lead their user to the name of the mineral whose characteristics he has 
observed under his microscope. It is a “ guide to the identification of 
minerals, rather than a summary of their properties.” The plan made 
use of in the construction of the tables reminds one of the schemes 
familiar to the determinative botanist. Habit, color, lustre, character 
of double refraction, etc., serve to place the minerals in different groups, 
from which one whose name is sought is selected by its special char- 
acteristics. The tables appear to fill a want, but only constant use in 
the laboratory will prove whether or not they will assist the student to 
the extent hoped by the author. 
Mineralogical News.—Azurite with the habit of Chessy crystals 
and large cerussites prismatic in the direction of the brachydiagonal 
are mentioned by Molengraff* from Willow’s silver mine near Preto- 
ria in the Transvaal. On the former the three new planes rs P>,—2 
P} and + P> occur. 
On three highly modified crystals of phosgenite from Monte Poni, 
Sardinia Goldschmidt” has discovered the new forms P$ and 3 P$ 
The distribution of the more common faces seems to point to a trape- 
zohedral symmetry for the crystals, but no circularly polarizing effects 
could be detected in them. The axial ratio determined from the 
mean of the best measurements is a: e= 1 : 1.0888. 
An analysis of jarosite from the cavities of the auriferous quartzite 
of the Buxton Mine, Lawrence Co., i D., has been made by Headdon.” 
His results are: 
SO, AsO, Fe,0, Ca0 NaO K,O H,O Total 
30.29 251 49.28 462 1.57 11.24 = 99.93 
SF. Loewinson-Lessing’s: Tables for the Determination of Rock-Forming 
Minerals. Translated by J. W. Gregory, With a chapter in the ese 
Microscope. London & N. Y., MacMillan & Co., 1893. Pp. 
18A mer. Jan Sci., XLVI, 1893, p. 24. 
