Granites from British Columbia, etc. 353 



twinned feldspar, presumably orthoclase. It has also been 

 found partly surrounded by quartz, but never completely 

 embedded in that mineral. All three minerals, muscovite, 

 epidote, and calcite, frequently occur associated and inter- 

 grown, all having apparently a similar origin, the calcite, 

 like the other two, apparently growing into the other 

 constituents of the rock. 



Figure 2 shows the mode of occurrence of these minerals 

 in this Pelly Eiver granite and their relation to the other 

 constituents of the rock. All the little inclusions and arms 

 in the central portion of the large muscovite crystal have 

 precisely the same orientation as the large plagioclase 

 individual which here bounds the muscovite on one side, 

 having formed apparently at one time portions of the same 

 individual. 



FlGUHB 2. 



Section of the Granite from Pelly River x 42 diameters. 

 M — Muscovite. B— Biotite. 



E — Epidote. P — Plagioclase. 



C — Calcite. 



Muscovite occurring in skeleton crystals in plagioclase in 



