REPORT OF THK DIRECTOR AND STATU GEOLOGIST 



to this period. In the case of the corrosion zones around magnet- 

 ite there may be some question whether the garnet developed at 

 this time or earlier. 



Quartz occurs in the rock associated with garnet, as already 

 noted. But in addition there is much coarser, granular quartz 

 along with the granulated feldspar. None could be found which 

 could he definitely determined to be primary, most, if not all, of 

 it having recrystallized during deformation. On the other hand, 

 it is quite certain that the recrystallization has been nearly in 

 situ, and that in the original rock an equally large amount of 

 quartz was present. Some few large individuals found with 

 large, uncrushed labraclorites would seem in all probability pri- 

 mary. A rough estimate of the amount present in the rock 

 would give a range from none to 15$ with an average of at least 



A farther indication of the considerable amount of recrystalli- 

 zation which the rock has experienced, is furnished by the occa- 

 sional presence of quartz inclusions in feldspar and even in horn- 

 blende and augite, quite after the fashion of the inclusions in 

 many of the gneisses. 



Gabbroic rocks containing quartz have been described from 

 several localities in many parts of the world; hence this occur- 

 rence is by no means unique. Yet it is exceptional and import- 

 art. Notwithstanding the amount of quartz, it is by no means 

 certain that the rock is more acid than the ordinary anorthosite. 

 If from 3$ to 5$ of alumina was replaced by iron in the ordinary 

 anorthosite magma, an excess of silica which would crystallize 

 out as quartz would result. .That this anorthosite-gabbro was 

 derived from the same parent molten mass as produced the anor- 

 thosite, is beyond question. 



The writer has previously called attention to the great similar- 

 ity between the eruptive rocks of the Adirondacks and those of 

 the Ekersund-Soggendal district in Norway, recently exhaustively 

 described by Kolderup. 1 This writer describes a quartz-norite as 



^volderup, C. F. Bergens museums Aarbog. 1S96. Die labradorfelse 

 des westlichen Norwegens. 

 dishing, H. P. Bui. geol. soe. Amer. 10:190. 



