450 THE CETSTAL FALLS lEON-BEAEING DISTEIOT. 



In the Fence River area the lower portion of the formation consists of 

 qnartzite, more or less ferruginous and micaceous. It contains beautifully 

 rounded and enlarged grains of quartz, and also less abundantly rolled 

 grains of microcline. Muscovite, biotite, and epidote occur, with the gen- 

 eral background of interlocking later quartz. The more ferruginous layers 

 have a groundmass almost exclusively of hematite, in which the clastic 

 particles are set. The hematite is in parallel micaceoiis scales, which com- 

 pletely cover the cleavage surfaces. Above these layers come crystalline 

 actinolite-schists and griinerite-schists, the former with garnets aiid both 

 carrying particles of the iron oxides. These rocks are not distinguishable 

 in the field or in thin section from certain varieties of schists of common 

 occurrence in the Negaunee formation of the Marquette district. 



