184 Canadian Record of Science. 



sively confined to the edge of the area, but also occur 

 abundantly in certain places towards the centre. They 

 consist of quartz, orthoclase, and often some iron ore, and 

 are quite different in composition, and apparently indepen- 

 dent of the anorthosite through which they cut. A number 

 of pegmatite veins in the township of Wexford, contain the 

 same bisilicates as the anorthosite but with quartz and pot- 

 ash feldspar. None of the rare minerals which frequently 

 occur in such veins were observed with the exception of a 

 substance resembling allanite in thin section of a single 

 hand specimen. 



About the line of contact, in the Township of Wexford, 

 in the prolongation of the strike of the large band of gneiss 

 which comes in between the main mass of the anorthosite 

 at.d the arm-like extension of the same, are many large 

 masses of orthoclase gneiss enclosed in the anorthosite, an 

 additional proof of the eruptive character of the anorthosite, 

 if such be needed. 



The anorthosite as well as the gneiss which it breaks 

 through are also cut by numerous dykes of diabase and 

 augite porphyry. 



To sum up, we have in this area a large intrusive mass 

 of anorthosite which cuts through the Grenville series, en- 

 closes large blocks of gneiss, sends out arms into the sur- 

 rounding gneisses, and in manyplaces is bounded by what 

 appears to be a peculiar contact product. 



MlNERALOGICAL CHARACTER OF THE MoRIN ANORTHOSITE. 



The anorthosite of this area exhibits a great variation in 

 structure and colour and in certain places even a consider- 

 able variation in composition, but is in mineralogical com- 

 position a gabbro, or norite, free from olivine and very 

 rich in plagioclase. Hand specimens from about fifty dif- 

 ferent places in this anorthosite area have been sliced and 

 microscopically examined and the following description of 

 these rocks is based on the results thus obtained. The 

 number of minerals which the rock contains is not large, 

 the variations in composition resulting principally from 



