Petrological Abstracts and Reviews 



ALBERT JOHANNSEN 



Washington, Henry S. "The Charnockite Series of Igneous 

 Rocks," Amer. Jour. Sci., XLI (1916), 323-38. 

 Five specimens of typical representatives of the charnockite series of India 

 from the original localities are here re-examined by Doctor Washington, and 

 five new analyses are given. A comparison with the older analyses shows 

 considerable variation. The rocks were also determined by the Rosiwal 

 method. The percentage of minerals given for the hj^persthene-granite 

 (charnockite) places the rock in 226' of the reviewer's system, a normal hjrpers- 

 thene-granite. The feldspar of the intermediate charnockite or hj^persthene- 

 quartz-diorite is not determined separately in percentages. The total feldspar 

 is given as 55.5 per cent, but from the description it is impossible to determine 

 the proportions. From the name given to the rock and from the statement, 

 "a great majority of the feldspar grains had a refractive index of about that 

 of AbjAui," the proportion of alkali feldspar must be small, although the 

 statement is made that "the feldspar is, apparently, largely alkaUc, some of 

 it showing the microcline grating, while the greater part shows no twinning 

 lamellae." Further in the summary, the range of the rocks is said to be 

 "through hypersthene-quartz-diorites (and possibly monzonites), etc.," 

 indicating the possibihty that the position of the rock is farther toward the 

 orthoclase side than the name quartz-diorite would indicate. Basic char- 

 nockite gives a mode corresponding to 3312, or normal norite, assuming the 

 feldspar is 95 per cent or more labradorite. The hornblende-hypersthenite 

 or bahiaite is 426. 



Washington, Henry S. " Persistence of Vents at Stromboli and 

 Its Bearing on Volcanic Mechanism," Bull. Geol. Soc. Amer., 

 XXVIII (191 7), 249-78, pis. 4, figs. 15. 

 It is pointed out that the vents of Stromboli have been persistent in location 



for a very considerable time. They cannot, therefore, have originated by 



explosive agencies, but can best be explained on the basis of the "gas-fluxing" 



hjTpothesis of Daly. 



Washington, Henry S. "Italian Leucitic Lavas as a Source of 



Potash," Metallurgical and Chem. Engineering, XVIII (19 18), 



No. 2. Pp. 21. 



The ItaUan volcanoes contain at least 10,000,000,000 tons of K2O, which 



at the present rate of consumption could "on paper" supply the United 



States for 50,000 years if a profitable method of extraction could be found. 



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