436 THE JOURNAL OF GEOLOGY. 



the various geological journals. In 1835 Gustav Rose 1 separated 

 the rocks composed of labradorite and hypersthene, with acces- 

 sory olivine, mica, apatite and ilmenite, from the gabbros, and 

 included them under the name " Hypersthenfels," at the same 

 time suggesting that the term gabbro be confined to rocks con- 

 taining labradorite and diallage. Many rocks were described as 

 hypersthenites or hypersthene rocks, because of the supposition 

 that the highly foliated augite in them really belonged to this 

 variety of pyroxene. Delesse 2 and others showed that the com- 

 pact feldspar of Haiiy, and the jade mentioned by von Buch as 

 an essential constituent of gabbros (afterwards called saussurite 

 by de Saussure Jr., and by Beudant) is in some cases a true 

 plagioclase ; and Hunt 3 showed that in other cases it consists of 

 zoisite, of white garnet mixed with serpentine, or of meionite, 

 and that the rocks containing these substances usually also con- 

 tain hornblende, with the characteristics of Rose's uralite. 

 Hunt, further, declines to regard the rocks containing a triclinic 

 feldspar and pyroxene (either augite, hypersthene or diallage) 

 as true gabbros. He places them among the dolerites, and 

 declares that the true euphotides described by Haiiy and de 

 Saussure are mixtures of smaragdite and saussurite ; a declara- 

 tion that Cocchi 4 made for the Tuscan rocks a few years later. 

 Rocks composed essentially of diallage and saussurite Cocchi 

 called granitones. Whatever may be the virtue of the objec- 

 tions raised to the use of the name gabbro for plagioclase- 

 diallage rocks, it still continued 5 to be applied to rocks thought 

 to be of this composition, just as hypersthenfels or hypersthenite 



1 Ueber die Gebirgsarten, welche mit den Namen Griinstein und Griinsteinporphyr 

 bezeichnet werden. Poggendorf 's Annalen, XXXIV., 1835, p. 16. 



2 Recherches sur 1' Euphotide. Bull. Soc. Geol. d. France, VI., 1848-4Q, p. 547. 



3 T. S. Hunt. — On Euphotide and Saussurite. Am. Jour. Sci., 2d Series, Vol. 

 XXV., 1858, p. 437; and Contributions to the History of Euphotide and Saussurite. 

 Ibid., XXVII., 1859, p. 326. 



4 1. Cocchi. — Description des roches igndes et sedimentaires de la Toscane dans 

 leur succession geologique. Bull. Soc. Ge"ol. d. France (2) XIII., 1856, p. 267. 



5 Cf. P. Keibel. — Analysen einiger Griinsteiner des Harzgebirges. Zeits. d. 

 deutsch. geol. Ges. IX., 1857, p. 569. 



