A peculiar form of crystalline quartz first recognized in this rock by a distinguished German petrologist, the late Prof. A. von Lasaulx, who visited the district in 1876.
To one accustomed to public speaking, the lecturers will often appear far below the standard of mediocrity in their manner. Though such men as Lasaulx in Munich, Häusser in Heidelberg, Droyson and Werder in Berlin deliver their lectures in a style that would grace the lecture-room of any country, yet the great majority are far, very far, from any eloquence in their delivery.
This seems to suggest an origin of the two sets of lavas from a different deep-seated magma; the presence of leucite in such large quantity requiring a magma in which soda is in excess, as compared with that from which the lavas of Etna have been derived. Mémoires pour Servir, etc., vol. ii. Daubeny, Volcanoes, p. 270. Von Waltershausen, Der Ætna, edited by A. von Lasaulx.
The MS. having been put into the hands of the late Professor Arnold von Lasaulx by the publisher of the atlas, it was subsequently brought out under the care of this distinguished petrologist, who was so fully fitted for an undertaking of this kind.