Merrill.] 
458 
[April 5 , 
some augite, but I think that this carries none. I think it not 
unlikely that Mr. Wadsworth mistook an epidote fragment for 
augite which it somewhat resembles ; 1 mv reasons for thinking so 
are these : I find nothing else throughout the section resembling 
augite, but there is more of the epidote substance to be found. 
In a duplicate slide, recently prepared, no augite was found, but 
several epidote fragments. The hornblendes are pretty well 
defined although they have become somewhat fibrous. Biotite 
may be found in considerable quantity, especially in the newer 
section, and I think it evident that some of the greenish substance 
is from mica altered into chloritic material ; in the center of such 
green separations could be seen, sometimes, remnants of fresh 
biotite with its fibres parallel to, and coincident with, those of 
the green alteration product. The feldspars are quite fresh and 
splendidly striated. Quartz is pretty abundant. To call a rock 
“ macroscopically and microscopically a diabase ” which carries 
no (or even “some”) augite, or its alteration products, certainly 
gives evidence that a new classification has been adopted ! 
I cannot understand how Mr. Wadsworth can regard specimen 
No. 164 as an “andesitic ash.” 2 I think that it is a diorite, as 
called in the Report, though not a very fresh one. No. 167 Mr. 
Wadsworth regards as a metamorphosed fragmental rock 3 instead 
of a diorite as it is called by Zirkel. I think it is probably a dio- 
rite with its feldspars much altered and with much quartz, some 
of which may be secondary. 
Mr. Wadsworth speaks of No. 187 as being so much altered 
that its diagnosis is difficult as Zirkel evidently found. Now this 
rock is, I find, a very simple though beautiful diorite. It is more- 
over a pretty fresh rock and consists almost exclusively of bright 
green hornblende with often splendid cleavage well preserved, and 
bright, distinctly striated feldspars. In Professor Zirkel’s lively 
description 4 of this specimen I cannot find the slightest token of 
his having found its diagnosis difficult. Mr. Wadsworth regards 
the hornblende as an “ alteration product ” ! 5 
1 This fragment could not well be definitely proved, optically, to be epidote, as it lay 
in the section. It seemed to consist of two different portions, one of which was charac- 
teristically pleochroitic. The other portion did not show this pleochroism. 
2 These Proceedings, Vol. xxi, p. 257. 
3 Ibid. 
4 Report, p. 92. 
5 These Proceedings, Vol. xxi, p. 258. 
