﻿184 NEW YORK STATE MUSEUM 



small amounts of hornblende, muscovite, zircon and pyrite. The 

 femic minerals constitute 15^ of the rock analyzed. The feldspar 

 is chiefly microcline and oligoclase, though with some microper- 

 thite. Both feldspars occur as augen, with trains of granulated ma- 

 terial running away from them, between which are foliae of quartz, 

 feldspar and biotite. To a considerable extent the quartz and 

 biotite seem to have resulted from recrystallization of feldspar. 

 The certain Alexandria syenite runs into very gneissoid and mica- 

 ceous border phases, which lie between its massive core, and the 

 augen gneiss beyond. These varieties are much more micaceous, 

 and much more quartzose than the massive portion, and in them 

 also much biotite and quartz have resulted from feldspar re- 

 crystallization. They are thus very similar to the augen gneiss. It 

 was this apparent gradation from one rock to the other in the field 

 which gave us the impression that the whole represented a single 

 intrusion. It is a matter of very minor importance in the local 

 geology, and must for the present be left as undetermined. 



Granitized amphibolite and amphibolitized granite (soaked 



rocks) 



Practically all observers who have worked in Laurentian areas, 

 have seen and recorded the evidences, which meet one on every hand, 

 of the attack of the granite upon the amphibolite inclusions, large 

 and small, which occur nearly everywhere, and are often abundant. 

 The action consists of an injection of granite into the amphibolite, 

 at first along the foliation planes, from which the granite spreads 

 out more or less into the adjacent rock, injecting itself between and 

 inclosing the grains, but with the distinction between the two ma- 

 terials still sharp. In later stages this sharpness disappears, the 

 two materials seem to merge, or fade into one another, and as a 

 final stage a rock is produced which seems a true mixed rock, in 

 which a distinction between the two elements is no longer possible, 

 and whose origin would be problematic except for the occurrence 

 of the less advanced phases of the change. Needless to say the 

 granite must be very thoroughly molten in order to produce these 

 mixed rocks. It was our purpose to investigate these rocks some- 

 what thoroughly chemically. Unfortunately however no material 

 which seemed to us sufficiently fresh to warrant chemical" investi- 

 gation was obtained from rocks which seemed distinctly interme- 

 diate. A beginning was made, however, by the investigation of two 

 rocks, one a granite slightly tinctured with amphibolite, and the 



