On Nepheline-Rocks in Brazil, with Special Reference to the Association of Phonolite and Foyaite

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Abstract
The nepheline-rocks heretofore recognized in Brazilian territory are the phonolites and associated basalts of Fernando Noronha, a deep-sea island off the north-eastern shoulder of the continent, in lat. 3° 5′ S., long. 32° 24′ 19″ W., the volcanic nature of which appears to have been first recognized by Darwin in the ‘Voyage of the Beagle’. Recently a single small pebble from the little-known island of Trinidade, in lat. 20° 31′ S., long. 29° 19′ W., has come into my hands, showing that phonolite of somewhat different character from that of Fernando Noronha occurs at that place also. Recent investigations have shown that nepheline-rocks of a somewhat different character are also abundantly developed on the mainland, and in such favourable conditions as to throw light on the relations of the granitic type of foyaite or elmolite-syenite to the other members of the group. The localities in which they have thus far been recognized are situated in the Provinces of Rio de Janeiro, São Paulo, and Minas Geraes, and their relative position and relation to the main orographie lines of the region in which they occur are shown in the accompanying sketch map (fig. 1). Three of these localities, Campo Grande, Cabo Frio, and the peak of Tingua, are in the immediate vicinity of Rio de Janeiro, the latter being in the Serra do Mar range, the two former among its foot-hills. Further south another set of localities occurs in the same range in the valley of the river Iguapé. In the

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