PETROLOGICAL ABSTRACTS AND REVIEWS 
ALBERT JOHANNSEN 
WASHINGTON, HENRY S. ‘‘Some Lavas of Monte Arci, Sardinia,” 
Amer. Jour. Sci., XXXVI (1913), 577-90, analyses. 
The extinct volcano Monte Arci has not been described since 1857. 
It consists of a core of rhyolite with later dacites, andesites, trachytes, 
and basalts. The various lavas are described petrographically and 
chemically. Seven analyses are given and they are recomputed in the 
C.I.P.W. system. 
WASHINGTON, Henry S. “The Composition of Rockallite,”’ 
Quart. Jour. Geol. Soc., LXX (1914), 294-302. 
This paper describes a peculiar aegirite-granite from Rockall. A 
chemical analysis gives SiO. 69.80, while a previous and probably 
accurate analysis of the other half of the same specimen gave 73.60. 
This shows the great variation possible in a single small specimen. 
WASHINGTON, Henry S. ‘An Occurrence of Pyroxenite and 
Hornblendite in Bahia, Brazil,’ Amer. Jour. Sci., XX XVIII 
(1914), 79-90, analyses. 
Describes a hornblendite with a border of pyroxenite intruded in 
gneiss. The rocks contain considerable manganese. They are interesting 
since they possess absolutely no feldspar and yet show from 18 to 30 
per cent in the norms. 
WasHINGTON, Henry S. “TI Basalti Analcitici della Sardegna,” 
Boll. Soc. Geol. Ital., XX XIII (1914), 147-67. 
A translation of ‘The analcite basalts of Sardinia”? which appeared 
in this Journal, Vol. XXII (1914), 742-53. 
471 
