ON GLAUCOPHANE. 95 



Genoa, and found in the groundmass " rather fibrous or filmy patches, 

 many of which show a peculiar blue colour." " On testing for 

 dichroism," he came to the conclusion that "there can be no doubt 

 it is glaucophane" and of a secondary origin. Prof Bonny was, per- 

 haps, the first who had spoken of a secondary glaucophane, and his 

 very specimen from Italy, has a close resemblance to that of Musashi, 

 as may be judged from his descriptions, as flir as the groundmass is 

 concerned. 



A fresh portion of our diallage has been mechanically separated 

 by the Thoulet solution, and a chemical analysis prosecuted by the 

 writer in the laboratory of Prof W. Knop in Leipzig, gave the 

 following result : — 



SIO, 46,40 



J/2O3 15, 59 



^'^ "l 12,62 FeO>Fe,0, 



MgO 7,15 



Ca 13, 52 



Na^O 2, 23 



A'2 0, 93 



H^ 1, 60 



100, 04 



As it contains over 2 °/o of Na^ 0, it approaches in its chemical 

 composition to an alkaline augite, and to this very fact the formation 

 of the secondary glaucophane may be attributable. 



III. Melaphyre. 



We have still another occurrence of glaucophane to be considered, 

 and this is in the melaphyre-enclosure in a slate at Akaya, east of 

 Omiya, Musashi pi'ovince. 



