300 Canadian Record of Science. 



case of their occurrence unaccompanied by phenomena of 

 pressure has more weight than a hundred where distinct 

 signs of pressure are found, since the latter may have 

 been developed subsequently ; nor can they be considered 

 as contact phenomena, since they are found everywhere 

 about the olivine wherever the latter occurs in the rock. 

 The occurrence above described is, for example, as already 

 mentioned, 12 miles distant from the nearest contact with 

 the gneiss. Lacroix has also pointed out this phenomenon 

 in some French olivine gabbros which he investigated. 

 It would seem therefore, that their origin is to be referred 

 to the influence of the plagioclase magma upon the olivine 

 before complete solidification. The so-called opacite rims 

 which occur about the horneblende and biotite in so many 

 eruptive rocks are evidently phenomena of a somewhat 

 analagous nature. 



In many places in this anorthosite area ilmenite 

 deposits were found, some of them of considerable extent. 

 The largest of these is on the north shore of the Saguenay 

 and about 15 miles in a straight line from Lake St. John, 

 where it forms a series of low hills. The ore contains 

 also olivine and plagioclase irregularly distributed through 

 it, and forms three irregular bands, which are intimately 

 associated with a rock resembling diabase. The most 

 easterly of these three iron ore bands has a width of not 

 less than 80 paces. Judging from its mode of occurrence 

 and composition this iron ore is in all probability of 

 igneous origin, as in the case of the iron ore of the Morin 

 area, which has been already described, the well known 

 ores of Taberg in Sweden, as well as those of Cumberland, 

 Ehode Island. 1 



We here find again all the structural varieties that 

 were described in the discussion of the Morin area, 

 namely : The massive rocks with a uniform size of grain, 

 the massive rocks with variations in the size of grain 



i M. E. Wadswofth, Ball., Mus. Comp. Zool., Harvard, May, 1881. 



