ing but faintly on polarized light, gives them the appearance of 
being imbedded in a light greenish glass. 
In the limited bed on the north side of Atlantic and Centre 
Hills, bomb-like masses of melaphyr are highly amygdaloidal, 
the amygdules varying from 1 to 5 mm. in diameter. These 
I regard as true amygdules. They are filled mainly with 
quartz and chlorite, though often a little epidote is present. 
In such cases the quartz occupies the outer zone with the 
chlorite and epidote interiorly. The ground-mass of this rock is 
an extremely dense, dark brownish gray, amorphous material 
bearing minute feldspar microlites. 
'The pseudo-amyedules of this melaphyr are commonly much 
elongated, and contain epidote and chlorite with more or less 
quartz. The epidote occurs as minute crystals, a single row of 
which often forms a border around the wall of the cavity ; while 
the entire central portion is occupied by the very compact, light 
green chlorite noted above. Outside of the amygdules or seg- 
regations of both kinds, scattered through the entire mass of the 
rock, are the common decomposition products, ferrite, opacite, 
viridite and kaolin. 
A typical sample of melaphyr from this area, but bearing 
some secondary quartz, which could not be avoided, yielded 
50.47 per cent. of silica. 
Second and Third Melaphyrs, Central Area.— The mel- 
aphyrs of this area are usually of a deep greenish color and often 
highly amygdaloidal; but they vary greatly in both color and 
texture. A common type is a. dark purplish gray rock, which 
is also often profusely amygdaloidal. Under the mieroscope 
its color is seen to be due to the large amount of opacite and 
magnetite in the ground-mass. Secondary epidote is abundant 
in comparatively large grains, which are often surrounded by a 
dense black border of opacite. The amygdules are filled with 
quartz, epidote and feldspar. The quartz and epidote prevail 
and occur in the form of an extremely fine grained and compact 
aggregate having a specific gravity of about 9.9. The iron 
