500 General Notes. : [May, 
tween nt and chromite. Both are translucent with a brown 
color when sufficiently thin, but the latter only with considerable - 
difficulty. The suggestion is made that the chromite may be an 
alteration-product of picotite. 
Chapter fourth deals with the fourth rock-species, Basalt, of 
which, however, only such as are of meteoric origin are treated 
in the present portion of the work. Pages I-xxxul at the 
close of the book contain valuable tables of all the chemical 
analyses hitherto made of the rocks described. Eight plates with 
forty-eight colored figures represent the microscopic structure of 
these same rocks in an admirable manner 
MINERALOGICAL Notes.—Quartz. Professor G. vom Rath, of 
the University of Bonn, has recently made a valuable contribu- 
tion to the literature of American mineralogy by his studies of 
the quartz crystals from Alexander county, N. C., material for 
Kunz, of Hoboken. The crystallography of these 
quartzes is very varied and complicated, and the writer does not 
hesitate to pronounce this American locality the most interesting 
one thus far known in the world. The tetartohedral character of 
this mineral is frequently shown by the large development of the 
trigonal trapezohedron —2P 3 2. Complicated twins and e 
acute EOE especially 3R, are also c 
Much new mate- 
part of Death valley, Inyo county, California. An exhaustive 
mon ograph on its crystallography, by Professor A. Wendell 
Jackson enumerates thirty-eight forms (of which P3, given 
in the Am. Four. Sci. for Dec. is not one). Of these fourteen were , 
independently observed by vom Rath,’ and twenty by both Hjort- 
dahl, of Christiania and Arzruni® of Breslau. Vom Rath and Bode- 
wig give the plane of the optical axes as perpendicular to æ P œ% 
making an angle with ẹ in the obtuse angle £ of 82° 42’, for so- 
ž api aai Notizen. Verhandlungen des Natur. Vereins d. preuss, Rhein- 
land und Westph., 1884. Bonn, 1885. 
2 Bulletin of a! California Pare of Sciences, No. 2, Jan., A 
PE ae rare d. Natur. Vereins d. preuss. Rheinland e ene P. 333» 
_ „*Zeitschrift für Krystallographie, Vol. x, 1885, p. 25. 
: — d., Natur. Verein d. preuss. Rheinland and Westph., p. 342, 
m 
