phalen] 



NEW OCCURRENCE OF UNAKITE 



313 



replaced feldspar, in addition to their occurrence in the body of this 

 mineral, form a fringe about the massive feldspar, and thus the 

 gradual replacement of this mineral may be plainly seen. 



The epidote is usually of a transparent yellowish green, but occa- 

 sionally becomes dark green and opaque in the vicinity of the iron 

 oxide, due perhaps to chloritic matter or to a larger content of iron 

 oxide, most probably the former. The iron oxides show fractures 

 filled with the same green pigment mentioned above; I judge them 

 from this fact to be secondary and to have resulted from the same 

 processes which have given rise to the green pigment. Some of 

 the epidote is nearly colorless; other portions are striped by a 

 darker variety along the cleavage cracks. These cleavages, when 

 present, are very poorly developed, as is to be expected in secondary 

 epidote, and for the same reason this origin interferes with the normal 

 coloring. Hence vibrations may vary in different parts of the rock, 

 but those noted are shades of yellowish green with absorption 

 B> C>A. 



The feldspar seems to be all orthoclase. It is almost perfectly 

 clear in part, but when epidotization has begun, it is translucent. It 

 is not colored in thin section, and the old-rose color noted in hand 

 specimens is to be explained by microscopic inclusions of flakes of 

 brown iron oxide, occurring in cloud-like masses more or less con- 

 centrated along the cleavage cracks. 



The remaining constituents are quartz, brown and black iron ore, 

 brown zircons, and apatites. 



For convenience in comparison the analysis of unakite is given 

 with that of hypersthene-akerite. 



