OF DENISON UNIVERSITY. 
9 
and yellowish isometric crystals of alteration product not yet further 
determined. 
The second sample taken nearer to the soapstone quarries, is a 
fine grained crystalline rock, brownish gray color with here and there 
groups of garnets of a rusty appearance. Talc is perceptable to the 
unaided eye. Under the microscope we find the field mainly horn- 
blende of a brownish color, all more or less altered. An unresolvable 
mass of “opacite” is scattered through it. Also numerous large scales 
of talc more abundant in this than in the former sample. Some scales 
of biotite, quartz, magnetite crystals, a little muscovite and a few 
small garnets. 
The next rock is the steatite rock itself. In hand sample it pre- 
sents a felting of stellate or rosette masses of crystals, of light greenish 
gray with brownish or orchre colored aggregates at centre of rosettes. 
The whole has an unctuous touch. Microscopically, it is seen to be 
almost wholly talc with here and there large crystals showing traces of 
the form of original hornblende. 
Comparing our studies of these three rocks, we find the first an 
Actinolite schist with the hornblende almost pure and containing trem- 
olite and a few talc crystals ; and as we draw nearer to the soapstone, 
we find the rock to contain hornblende all more or less altered with 
more talc present, making it a talc schist, until we reach the pure talc 
rock containing but few traces of the original hornblende structure. 
Followed consecutively, the change would probably not be so appar- 
ent, but from these samples taken at different distances from each oth- 
er the change is quite marked, and we conclude that the soapstone 
was formerly a gneiss or schist and that its present condition is due to 
the alteration of the hornblende to talc brought about by atmospheric 
or hypogene forces. Whether the period occupied in bringing about 
the transformation was of long or short duration we cannot say. 
In this series of rocks we find the points of interest to be the inter- 
penetration and the pereklite twinning of the plagioclase crystals, 
some of which in the first diabase studied are evidently formed under 
pressure ; the polysomatic structure of the augite in both diabases ; 
the absence of garnets in the diabase and their presence in the adja- 
cent genisses, schists and diorites where ever studied, in which our ex- 
perience differs from that of Mr. Lawson in his article in the April 
Geologist^ where he says he finds garnets in the central portion of the 
dyke studied by him and none in contact rocks or schists, this leading 
