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264.-- G. HH. Williams—Pyrowene and Hornblende.. 
a 
original crystal being simple, the secondary mineral all has the 
same optical orientation 
Fig. 2 exhibits a similar case of ae a ame of a 
brown hornblende in another section of the sa 
erystals are cut nearly perpendicular to their perieal axes pi 
show very plainly that their orthopinacoids are parallel. The — 
change has here taken place in somewhat larger patches than 
in the former instance and the boundaries between the two — 
minerals are somewhat more distinct, but there can be little 
doubt that the process is the same i n both. ig 
These two cases described in some detail must be regarded 
as typical of a great variety of others, nearly or quite as 4 
which when taken together make the evidence of paramorpho- 
sis, at least as far as the “cide ta rock in question is concerned, 
very satisfactory. It has been already mentioned that thé 
- groundmass of this rock is composed almost entirely of roundeg 
2. 
Interspersed among 
these are frequent hypersthene poe of precis we: the same 
0 
blende, 
rablese™ 
the ptere alors owes bene that this was orig’ 
inally a hypersthene be up (norite), like others which occur i 
close connection with it, and “a its present form (diorite) has 
been due to gradual molecular seairpaten seems quite natural, 
although not perhaps capable of rigid pr P. 
everal peat 3 from other localities sie come to my novice 
which seem also to show strong indications of the direct one 
of pyroxene into compact hornblende. 
