142 G. H. Williams—Norites of the “ Cortlandt Series.” 
when of the extremest thinness. These rods are often curved 
and closely resemble the trichites seen in certain volcanic glasses. 
There is no parallelism whatever in the arrangement of these bodies, 
a fact which has an important bearing on their mode of origin. 
3. The dots.—These are extremely minute, opaque, globulitic 
bodies, which may be regarded either as very small plates or as 
the elements of which the rods arecomposed. They vary some- 
what in size, the smallest forming the fine reddish-brown dust, 
which imparts the characteristic color to the andesine and which 
no power of the microscope can resolve. These dots resemble 
the globulites in certain obsidians in the same way in which the 
rods resemble trichites. 
The mutual arrangement, of these three classes of inclusions 
throws considerable light on their nature and origin. As above 
remarked, there seems to be no regularity in their direction, as 
would be required by the “‘solution planes ” of Judd; and yet 
there is a very decided regularity in their arrangement in zones 
in the enclosing crystal. As a rule, the center of the plagioclase 
individuals is occupied by an indiscriminate mass of rods and 
plates, which .is surrounded by a zone filled only with reddish _ 
dust. Outside of this there is almost always an exterior zone 
quite free from inclusions of any kind. This arrangement is 
essentially the same as that recently described by the writer in 
the bytownite of the Baltimore gabbros.* 
The dust-like globulites are also present in the space between 
the rods and plates near the center of the crystal. Then, how- 
ever, there is always a perfectly clear space around each larger 
inclusion and the width of this clear zone depends upon the size of 
the inclusion which tt surrounds. It is widest about certain 
occasional octahedral crystals of magnetite (see fig. 3). The 
bearing of this phenomenon upon the mode of origin of the in- 
clusions is too apparent to need further elucidation. 
The fact that the arrangement of these inclusions is altogether 
independent of the numerous bendings and cracks, mentioned 
above as so common in this feldspar, also speaks strongly 
against their secondary origin. 
A careful and prolonged study of the form, size and arrange- 
ment of these inclusions has convinced the writer that they are 
original and represent the form in which the iron first separated 
from the magma. This was probably simultaneous with the 
erystallization of the feldspar, as is indicated by the uniformity 
of their zonal arrangement. 
Such red globulitic dust is well known to be the coloring 
matter of the feldspar in many of the quartz porphyries. The 
sunstone of T'vedestrand owes its peculiar luster to plates of 
* Bulletin of the U. S. Geological Survey, No. 28, p. 21, i886. 
