26 G. W. Hawes—Albany Granite, 
are not at all constant, but the prevailing variety is a dark 
compact argillitic mica schist with andalusite crystals scattered 
through parts of it. Upon the summit of Mt. Willard they 
appear to be very uniform over a large area, and for this reason 
the specimens for chemical study were taken from this spot. 
he schists at the summit have a strike very nearly north 
and south, and they dip 60° to the west.* The line of con- 
tact with the granite runs in an irregular northwest direction. 
t a distance of 100 feet from this contact, with the exception 
of the rather rare andalusite crystals, no minerals are visible 
in this schist to the unaided eye, unless the glistening surface 
be considered as an indication of mica. Under the microscope 
it is seen to consist of quartz, muscovite (probably the variety 
containing combined water), and chlorite. Titanic iron par- 
tially decomposed into leucoxene, some magnetic iron which 
can be drawn from the powder with a magnet, and particles 
resembling coal or graphite, constitute opaque black ingre- 
dients. A little biotite and a very few crystals of tourmaline, 
recognized by form and the direction of strong absorption, are 
accessory constituents. No marked change is visible in the rock 
at a distance of fifty feet from the contact, but nearer than this 
point the effect of the contact becomes very soon evident. As 
the specimens described and analyzed were all, with the excep- 
tion of the normal schist at 100 feet, taken from the same 
stratum, I think that all the differences noted may be with 
certainty regarded as due to the effect of contact. 
wenty-five feet from the contact the schists are much 
changed in microscopic structure. They are more definitely and 
coarsely crystalline ; biotite becomes a more prominent con- 
stituent, and tourmaline crystals, blue within and brown with- 
* Strike of slate 12-22 W., strike of contact N. 77 W. Hitchcock’s Geology of 
New Hampshire, vol. ii, p. 177. ‘ 
+ I can not regard the conclusion of Prof. v. Lasaulx that this substance 18 
titanite of lime, titanomorphite, as certainly correct in all cases, for in rocks 
like this that are nearly free from lime the same decomposition takes place. In 
this case there is not enough lime in the whole rock to make titanomorphite with 
the titanic acid. 
