THE VOLCANOES AND ROCKS OF PANTELLERIA 
HENRY S. WASHINGTON 
Geophysical Laboratory, Carnegie Institution of Washington 
PART II 
PETROGRAPHY! 
The rocks of Pantelleria have been described in modern times 
only by Foerstner? and Rosenbusch.s Most of the names assigned 
by Foerstner are not in accord with present nomenclature or the 
rock characters. His “phonolites” contain so much silica that 
no nephelite could form, they being quartz-bearing instead, and 
his ‘‘andesites”’ contain no soda-lime feldspar, the triclinic feldspar 
present being a soda-microcline. His “‘liparites’”’ may best be 
considered as pantellerites—a group discovered by him, and with 
well-marked characters, though his synonym, “ dacite-liparite,” 
is open to the same criticism as his “‘andesite.’’ His basalts are 
normal feldspathic ones. 
Rosenbusch describes some of the rocks in detail, while others 
are only mentioned. He accepts Foerstner’s group of pantellerites, 
to which he refers his “‘liparites.’”” He remarks on the anomalous 
character of the “‘phonolites” and “‘andesites,”’ but retains Foerst- 
ner’s names, the highly siliceous composition of the former and the 
peralkalic character of the latter not being taken into consideration. 
The following rocks, named according to the Qualitative 
System, occur on Pantelleria, their positions in the Quantitative 
System being also given. They will be described in this order. 
* The specimens collected by me are supplemented by a set collected by Mr. F. 
H. Butler of London in 1891, and obtained from him in 1897. 
2H. Foerstner, Boll. Com. Geol. Ital., 1881, pp. 533-38. 
3H. Rosenbusch, Mikr., Phys., Vierte Aufl., II, No. 2 (1908), pp. 839, 851, 
926, 967, 1039, 1115, 1357. A few very brief descriptions are given by G. T. Prior 
(Min. Mag., XIII [1903], 254). 
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