Palache.] 



New Soda j Xmphibole, 



felJspar is water-clear, and contains many strings and bands of 

 liquid inclusions. Its chief characteristic, however, is the network 

 of needle-like fibers of pale green actinolite which traverses it in 

 every direction, and gives it its green color. It is this mineral 

 which forms the silky bands joining the ends of disrupted amphibole 

 crystals, mentioned above. It will be further considered in con- 

 nection with the blue amphibole. Flame tests on the vein feldspai 

 yielded results identical with those given by the albite of the matrix, 

 and fragments which were free from actinolite needles gave a spe- 

 cific gravity of 2.62$. It may thus also be considered as albite. 

 The boundary between the albite of the matrix and that of the vein 

 can, however, always be sharply drawn. The latter is always much 

 more coarsely granular, generally contains the actinolite fibers, 

 which are never seen elsew here in the rock, and is quite free from 

 the blue amphibole, from zircon, and from sphene. Fig. 1, Plate II, 

 shows the sharp contrast between the mass of the rock and the 

 intersecting vein. The veins are clearly secondary, their minerals 

 having been deposited either by segregation or by infiltration into 

 fissures formed in the rock after it had attained substantially its 

 present character. 



THE BLUE AMPH I UOLE. 



The blue amphibole appears in the thin sections most frequently 

 in sharply bounded lath-shaped crystals of a fine blue or yellowish 

 blue color. It is also seen in irregularly bounded prismatic indi- 

 viduals, and in rounded grains. In sections cut parallel to the 

 schistosity of the rock, transverse sections of the amphibole are 

 never seen, and the forms are uniformly prismatic, with very dis- 

 tinct cleavage cracks parallel to the prismatic axis, and with fre- 

 quent and, for the most part, sharp, transverse cracks or partings. 

 In sections cut at right angles to the schistosity basal sections of 

 the amphibole abound. They show generally a sharp boundary, 

 with the dominant form a prism, toP, of about 126 . The angles 

 of the rhomb are generally, but not always, truncated by the clino- 

 pinacoid, and very rarely by the orthopinacoid. Frequently, sev- 

 eral crystals are intergrown with the orthopinacoid in common, as 



