424 



France, and in a verd antique marble from a Roman ruin. The 

 association of nickel with the chromic iron and serpentines of Penn- 

 sylvania has been long known, and I have found the chromic iron of 

 Canada to contain small portions both of nickel and cobalt, although 

 the latter metal can rarely be detected in the nickeliferous serpen- 

 tines. 



The results of a number of analyses show that it is constantly pre- 

 sent in the talcose slates and steatites of this region, and the same is 

 to be observed of the magnesites and dolomites of the series ; indeed 

 the distribution of nickel would seem to be co-extensive with that of 

 the magnesia in this formation, and the same thing may be said of 

 chrome. I have not, however, met with any traces of chrome or 

 nickel in the serpentines and talcose rocks of the Lauren tian system, 

 which underlies the Silurian and the still older copper-bearing rocks 

 of Lake Huron, and probably corresponds to the oldest gneiss of 

 Scandinavia. Both chrome and nickel, however, characterize the 

 serpentines of the Vosges and of California. I have not yet been 

 able to examine specimens from other foreign localities. The pre- 

 sence of traces of nickel in certain talcs was long since noticed by 

 Stromeyer. Much of the so-called talcose slate of the Green Moun- 

 tains is not magnesian, but consists of a hydrous aluminous silicate 

 allied to pyrophyllite or pholerite, which are alumina-talcs. 



The euphotides, which are associated with many of the European 

 serpentines, are not wanting in the Green Mountains, although less 

 distinctly marked to the eye than the foreign varieties. A tough, 

 greenish or greyish-white rock, with a waxy lustre, forms in many 

 places great stratified masses, which are associated with the serpen- 

 tine, and is found on analysis to consist of a soda-felspar (albite) 

 with a silicate of lime, magnesia, and protoxide of iron, having the 

 composition of amphibole, thus constituting a veritable euphotide. 

 The two minerals are clearly distinguishable after calcination, which 

 blanches the felspar, and reddens the ferruginous silicate. These 

 rocks are by this means distinguished from others similar in their 

 appearance and mode of occurrence, but consisting of petrosilex or 

 compact siliceous felspar, and equally members of the sedimentary 

 series. The specific gravity of these euphotides shows that the 

 aaussurite or felspar which forms their base has a density not greater 

 than that of ordinary soda-felspar. 



