438 COSMOS. 



where lasted for five or six years, until renewed investiga- 



ous) trachytes {Description physique des Iks Canaries, 1836, p. 486, 

 487, 490, and 515). This lithological classification of the volcanoes 

 of the Andes and those of Mexico shows that, in a scientific point of 

 view, such a similarity of mineralogical constitution and the possibili- 

 ty of a general denomination ilerived from a large extent of country, 

 can not be thought of. A year later, when Leopold von Buch first 

 made mention in PoggendoriF's Annalen, of the name of andesite, 

 which has been the occasion of so much confusion, I committed the 

 mistake myself of making use of it on two occasions — once in 1836, 

 in the account of my attempt to ascend Chimborazo, in Schumacher's 

 Jahrbuch, 1837, s. 204, 205 (reprinted in my Kkinere Schriften, bd. i., 

 s. 160, 161); and again in 1837, in the treatise on the highland of 

 Quito (in Poggend., Ann., bd. xl., s. 165). "Recent times have 

 taught us," I observed, already strongly opposing my friend's con- 

 jecture as to the similar constitution of all the Andes volcanoes, 

 "that the different zones do not always present the same (mineral- 

 ogical) composition, or the same component parts. Sometimes we 

 find trachytes, properly so called, characterized by the glassy feldspar, 

 as at the Peak of Teneriffe and in the Siebengebirge near Bonn, where 

 a little albite is associated with the feldspar — feldspathic trachytes, 

 which, as active volcanoes, exhibit abundance of obsidian and pumice ; 

 sometimes melaphyre,and doleritic mixtures of Labradorite andaugite, 

 more nearly resembling the basalt formation, as at .^tna, Stromboli, 

 and Chimborazo ; sometimes albite with hornblende prevails, as in the 

 lately so-called andesites of Chili, and the splendid columns, described 

 as dioritic porphyry, at Pisoje, near Popayan, at the foot of the vol- 

 cano of Purace, or in the Mexican volcano of JoruUo ; finally, they 

 are sometimes leucite ophyrs, a mixture of leucite and augite, as in 

 the Somma, the ancient wall at the crater of elevation of Vesuvius." 

 By an accidental misinterpretation of this passage, which shews many 

 traces of the then imperfect state of geological knowledge (feldspar 

 being still ascribed to the Peak of Teneriffe instead of oligoclase, 

 Labradorite to Chimborazo, and albite to the volcano of Toluca), that 

 talented investigator Abich, who is both a chemist and a geologist, has 

 erroneously attributed to myself the invention of the term andesite as 

 applied to a trachytic, widely-dispersed rock rich in albite (Poggend., 

 Ann., bd. li., 1840, s. 523), and has given the name of andesine to a 

 new species of feldspar, first analyzed by him, but still somewhat enig- 

 matical in its nature, " with reference to the mineral (from Marma- 

 to, near Popayan) in which it was first observed." The andesine 

 (pseudo-albite in andesite) is supposed to occupy a middle position 

 between Labradorite and oligoclase; at the temperature of 55°'7 its 

 specific gravity is 2*733, while that of the andesite in which the ande- 

 sine occurred is 3*593. Gustav Rose doubts, as did subsequently 

 Charles Deville (Etudes de Liihologie, p. 30), the individuality of 

 andesine, as it rests only on a single analysis of Abich, and because 

 the analysis of the feldspathic ingredient in the beautiful dioritic por- 

 phyry of Pisoje, near Popayan, brought by me from South America, 

 ■which was performed by Francis (Poggend., bd. lii., 1841, s. 472) in 

 the laboratory of Heinrich Rose, while it certainly shows a great re- 

 semblance to the andesine of Marmato, as analyzed by Abich, is, not- 

 withstanding, of a different composition. Still more uncertain is the 



