LEME, SEAISHG WHA SIS WIE, JR(OCIES , SO ING. 9 
imbedded. The inclusions discoverable in them are magnetite, 
small masses of green and brown earthy matter, much of which 
seems to be in pseudomorphs after magnetite, tiny opaque dust 
inclusions, small elliptical glass-filled cavities and a few apatite 
crystals. No liquid inclosures were detected in any of the fresh 
grains, though a few may be present in those that are slightly 
decomposed. The twinning of the feldspar is less complicated 
than was to be expected after studying the olivine-bearing granu- 
litic rocks. Many of the grains are untwinned; more are simple 
Carlsbad twins; while a few show the more usual parallel bars of 
the polysynthetic twinning. Most of this feldspar is undoubtedly 
plagioclase of the same character as is found in the normal gabbro. 
Its optical properties so far as can be determined are like those 
of the gabbro feldspar, and the density of a powder separated 
from rock No. 8879 is 2.715. Some of the untwinned feldspar 
may be orthoclase, as analyses of some of the hypersthenic gran- 
ulitic rocks show a large percentage of potassa. 
The remaining primary component of these rocks is magnetite. 
It is found as tiny inclusions in the other constituents and as 
large grains between them, and sometimes within the pyroxene. 
The outlines of the grains often show traces of crystalline forms, 
but almost as frequently they exhibit none. 
In addition to the minerals mentioned there is also often 
present a comparatively large quantity of biotite, but in the 
hypersthene varieties it seems to be less abundant than it is in 
those containing none of this pyroxene. When present it is in 
brownish green flakes so intimately associated with the hyper- 
sthene and diallage that it must needs be regarded in some cases 
as an alteration product of them. Not only are the little flakes 
abundant on the peripheries of the pyroxene grains, but they are 
also disseminated all through their substance as very small ill- 
defined specks whose strong pleochroism and brown color pro- 
claim them to be biotite. In other rocks, in which the pyroxenes 
are fresh, the biotite is completely wanting, but in No. 7036, one of 
the freshest of all the granulitic rocks examined, the mica is very 
plentiful, particularly in the feldspar, as brown wisps and _ plates. 
