424 Canadian Record of Science. 



the rock consists almost entirely of plagioclase. Nearly 

 all the sections show a distinct cataclastic structure ; and 

 the remnants of the larger individuals of plagioclase are 

 sometimes still to be observed. Moreover, a few grains 

 of iron ore are always present, and in many other thin 

 sections a few grains of pyroxene, hornblende, or biotite 

 were likewise observed. A little quartz is also present 

 at times, and may be of secondary origin. 



The rock of Chateau Eicher occupies a peculiar position 

 in as far as its plagioclase, at least in one case, was more 

 acidic than in any of the anorthosite occurrences hereto- 

 fore investigated. Analyses made by Sterry Hunt are 

 noted on page 436, No. L, II., III. These analyses also 

 furnish the proof that the large individuals of plagioclase 

 and the crushed plagioclase, which forms the ground mass 

 or paste, have, as above mentioned, the same chemical 

 composition. 



(e) In the State of New York, U. S. A. 

 As early as 1842, Emmons mentioned in his " Keport 

 on the Geology of the Second District of the State of 

 New York," the presence of a large mass of this rock in 

 the County of Essex, New York. It occurs at the eastern 

 point of the large peninsula, or, properly speaking, island, 

 of Laurentian rocks, which, as above mentioned, here ex- 

 tend from Canada into the United States. The extent 

 of the area is such that its boundaries approximately 

 coincide with those of Essex County. Emmons gives an 

 excellent general description of the rocks in the area ; 

 but since his report was written long before the beginning 

 of modern petrography it refers only to their macroscopical 

 character. In the year 1876, Leeds, in his paper entitled 

 "Notes upon the Lithology of the Adirondacks," 1 gives 

 the results of a further examination of several hand- 

 specimens of these rocks, treating, however exclusively, 



1 Thirtieth Annual Keport of the New York State Museum of Natural History, 1S76. 



