GEOLOGY OF THE PARADOX LAKE QUADRANGLE 497 



The quartz sometimes occurs in grains, but more often, especially 

 in the crushed varieties, in lenses. Evidently in some cases the 

 quartz has been enriched secondarily. 



The structure is frequently cataclastic, the constituents appearing 

 to be in grains resulting from the crushing of larger crystals. The 

 rocks possessing this structure pass by insensible gradations into 

 true granites, and there can be little doubt that the gneisses exhibit- 

 ing this structure are crushed portions of the granite. 



The rock found in Pharaoh mountain is the most wide-spread type. 

 It presents a general pink appearance in the hand specimen, and 

 under the microscope proves to be a hornblende-granite-gneiss. 



The Pharaoh type contains about 50^ of feldspar. Predominating 

 orthoclase, with accessory albite or oligoclase, is probably the normal 

 composition, but these have usually been replaced by microcline and 

 microperthite. Primary quartz constitutes about 30^ of the rock, 

 although the actual quartz content is almost always increased by 

 the presence of secondary lenses and veinlets. The remaining 20^ 

 is made up of hornblende and the accessory minerals. 



Syenite. As already mentioned, the syenite of the Paradox 

 region belongs to the syenite type of Cushing and of Smyth. The 

 preliminary reports on the Paradox region were published before 

 this type was recognized, and it was included within the " doubtful " 

 area. 



In thin section a cataclastic structure is commonly found. There 

 is much variation in mineral contents, there being a complete grada- 

 tion from an augite syenite containing microperthite to a type closely 

 resembling the granite and consisting essentially of hornblende, 

 microperthite, subordinate augite, quartz and a little biotite. There 

 is constant likeness between this type and the granite of Mount 

 Pharaoh in the presence of intergrowths of several different min- 

 erals. Microperthite (consisting of intergrowths of orthoclase and 

 albite) is a normal component, and less frequently there occurs 

 (in the syenite only) an intergrowth of green augite with bronzite 

 or hypersthene. Quartz is usually present in the syenite, and its 

 often elongated lens-like form suggests that it is secondary. Some 

 primary quartz is present also. The pyroxene is a bright emerald 

 green variety. 



