G. W. Hawes— The Greenstones of New Hampshire. 187 
blende resulted from the pyroxene is shown by the spots of 
hornblende in the pyroxene; the outline of these altered spots 
is quite indefinite and indistinct, indicating plainly the fact of 
change. When change of species takes place with no change 
whatever of chemical composition, it does not follow that the 
alteration should begin at the outside as in other cases, and 
as here seen this change began at the middle. Other crys- 
tals are seen to have so completely changed as to develop 
beautifully the cleavage of hornblende, while at the same time 
a good illustration of the cleavage of pyroxene is seen in the 
same slide. This alteration, which is not uncommon in other 
regions, is of much importance in New Hampshire, for in nearly 
all the trap rocks, the same change has taken place. It will be 
noticed that the pyroxene changes into a yellowish-brown 
strongly dichroic hornblende, and not into the bright green 
one which characterizes the original diorytes. 
6. Argil/yte.—In closing, I give an analysis of one of the non- 
crystalline rocks which abound in the region, in support of 
some of the views that have been advanced. The one that I 
select is from Woodville, and is a corrugated argillyte. The 
composition obtained is as follows: 
faa ia rouis. sa let ee 
Mie Ss. Cur Sola oe ee ee 
Perie O¢x1d) ss ee “48 
errous oxide liv Se pote ee 
ime ... J la eu ee 
Moawnosia 2c cic cdi ek ee 
EES NOW te eee oe) fe gee 3°44 
OR ts Py ee ets ae ee 2°55 
Water i633 io bog pai nebo 3°66 
99°92 
_In this rock the microscope shows only incipient erystalliza- 
tion ; yet it a composition that would have made a 
I percentages of lime, magnesia and iron. 
_*0 conclusion, it appears from the facts described, that the 
greenstones of New Hampshire have been formed from fine 
0 
oa iments, has determined the character: of the greenstone . 
*ld Laboratory, New Haven, Conn. 
