372 General Notes. [April 3 
Wollastonite and melanite, which were observed in some of the 
nephelinites, Migge thinks must be looked upon as having crys- 
tallized directly from the magma of the rock itself, and not as the 
result of the solution of inclusions. Unfortunately, the author was 
not able to study these rocks in the field, so that their geological 
relations are not definitely known. Bruno Doss* has recently 
made a very thorough investigation of the igneous rocks of Pal- 
estine, and as a result of his studies declares them to be labra- 
dorite basalts. Their olivine constituent occurs both in porphy- 
ritic crystals and in the ground-mass. The two generations are 
distinguished by the marked differences in their mode of alter- 
ation. The mineral of the first generation contains more iron 
than that of the second, and accordingly gives rise to decompo- 
sition products consisting principally of red iron compounds in- 
soluble in acids, while the latter class are merely serpentinized. 
Twins of olivine were observed in which,the twinning planes are 
co, and in less frequent instances oP. In three specimens 
pseudobrookite was detected. The fact that quartz and oli- 
vine may occur in the same rock is given additional interest by 
the discovery in Northern California of a quartz-basalt.. This 
rock is described by Mr. Diller? as possessing all the essential 
characteristics of ordinary basalts, with the addition besides of 
numerous grains of quartz, many of which are surrounded by a 
zone of glass and pyroxene. From the fact that quartz is also 
found in bombs, which must have existed as clots in the lava at 
the time of its eruption, Mr. Diller is forced to assume that the 
of the substances of lithophysz and of spherulites is essentially the 
same, and therefore the former cannot have been produced by 
the alteration of the latter.——Chrustschoff 5 has isolated zircon 
` * Min. u. Petrog. Mitth., vii., 1886, p. 461. 
* Amer. Jour. Sci., Jan. 1887, p. 45. 3 Ib., Jan. 1887, p. 36. 
; ist, 
