136 G. W. Hawes—The Greenstones of New Hampshire. 
porphyritic, and sometimes large crystals of feldspar are sparsely 
scattered through the mass. 
e 
stratified kinds give us the plainest conceptions of the mode of 
origin of the whole. 
5. Metamorphic Doleryte.—There is one more massive rock to 
which I refer on account of its lithological interest. It is the 
compound of pyroxene, triclinic feldspar and titanic iron, which 
is found at Littleton. The rock has the com position of a 
color of this rock is quite dark gray, and large orbicular erys- 
talline masses of diallage are developed in a finely granular base. 
Its composition is as follows: 
Me es 40°25 
"ctrl gf CTA evens ie muitos Se our 13°62 
Pete Obs ce 5°46 
SrPOUn UNIO os; pour a a ce 10°36 
Piss e URES ro; 
ee 8°86 
Thee ARSON SMa eene sa 
_cnggn CE Saha: ae ee ea 1°96 
Ti Oe 6°53 
Water a “74 
98°68 
microscopic structure of this beautiful rock is illustrated 
in figures 3 and 4 o a - Fig. 3 represents the appear 
ance of a thin section magnified thirty-five diameters, by ordi- 
nary transmitted light, while fig. 4 represents the appearance 
of the same between crossed nicol prisms. It contains as the 
It is quite evident from a study o ae 
the colored mineral was originally all pyroxene, and that it has 
now been partly changed into hormblende. That the horn- 
