11-t Allen and Clement — Role of Water in Tremolite. 



readily understand how, by the rapid cooling of a melt of the 

 composition MgSi0 3 ," there is formed an anhydrous substance 

 having the properties of an amphibole and very closely resem- 

 bling kupfferite in particular., though the latter contains nearly 

 4 per cent of water. 



It has already been stated that the amphiboles analyzed by 

 Penfield and Stanley all contained water. The following are 

 their results : 



Actinolite, 



Hornblende, 



More recent results by Blasdale confirm these figures and 

 include also glaucophane :f 



Actinolite, Berkeley, Cab, H 2 above 100 = 1-78$ 



Greiner in Tyrol, 



H 2 



= 



l-81/o 



Russell, tf. Y , 



tt 



= 



1-60 



Kragero, Norway, 



It 



= 



1-81 



Pierrepont, N. Y., 



a 



zzr. 



1-42 



Cornwallis, N. Y., 



a 



— 



1-30 



Renfrew, Ont., 



a 



— 



•75 



Ellenville, N. Y., 



ii 



= 



•66 



San Pablo, Cal., 



tt 



ii 



a 



= 2-58 



Tremolite, " " 



tt 



it 



a 



= 2-25 



Glaucophane, " " 



a 



It 



tt 



= 1-18 



a a a 



it 



it 



a 



= 257 



A pargasite from Arroyo Hondo, Santa Clara County, Cal., 

 recently analyzed by W. O. Clark, gave 3*16 per cent H 2 

 above i00°4 



Two hornblendes analyzed by H. S. Washington gave results 

 as follows :§ 



Hornblende from Linosa Island near Tunis contained *19$ H 2 

 " " Kaersut, Greenland, " -59f H 2 



A hornblende from Beverly, Mass., analyzed by F. E. 

 Wright, contained 3"15 per cent H 2 0.|| 



These data are sufficient to show that tremolite, kupfferite, 

 actinolite, glaucophane and pargasite all contain water ranging 

 in quantity from 1*3 per cent to 3 per cent, most of which is 

 retained at 110°. Hornblende also contains water, though 

 usually in smaller quantity. In view of these facts it seems 

 not unlikely, that the water in all of them is not combined, but 

 dissolved as it is in tremolite. 



*This Journal, xxii, 406, 1906. At the time of its discovery this was 

 regarded by us as a true amphibole, since kupfferite was not then known to 

 contain water. 



f Contributions to the Mineralogy of California; Bull. Dep't of Geol., 

 Univ. of Cal., vol. ii, No. 11, pp. 333, 334, 338-340. 



X Paragenesis of Minerals in the Glaucophane-bearing rocks of California, 

 J. P. Smith, Proc. Am. Phil. Soc, xlv, 237, 1906. 



§ Private communication. 



|| Tschermak's Miner. Petrogr. Mittheil., xix, 312, 1900. 



