220 WATSON AND CLINE ROCKS OP THE BLUE RIDGE REGION 



which forms a part of the larger Blue Eidge petrographic province. Sim- 

 ilarity is again shown to the larger Blue Eidge province in the quartz of 

 the quartz-bearing members being either of blue or gray color. 



Again, the members of the charnockite series vary in composition from 

 granites to pyroxenites with a similar variation shown in the Blue Eidge 

 series, and in each province the rocks are hypersthenic. It must be stated 

 here, however, that while there is apparently a close correspondence in 

 mineral composition and in the variety of types in the two provinces, the 

 field relations of the several types to each other in the Blue Eidge prov- 

 ince are not yet conclusively determined. 



Unakite Type 



origin of name 



The name unakite was first applied by Bradley 31 in 1874 to "a member" 

 of the granitic series from the Great Smoky Mountains, a portion of the 

 Unaka Eange of the Blue Eidge, which range forms the boundary between 

 North Carolina and Tennessee." Bradley's description was based on 

 specimens seen from the slopes of the peaks known as "The Bluff," "Wal- 

 nut Mountain," and "Max's Patch," Cocke County, Tennessee, and Madi- 

 son County, North Carolina. His brief description of the rock (unakite) 

 is as follows : 



"The character relied on for the separation of the species is the constant 

 replacement of the mica of common granite or the hornblende of syenite by 

 epidote. The amount of this ingredient present is quite variable, in some cases 

 even exceeding one-half of the whole mass. The feldspar present is orthoclase 

 of various shades of pink, forming from one-fourth to one-third of the whole. 

 The quartz is mainly white, but occasionally smoky ; its isolated portions form 

 but a small part, say one-fourth of the mass ; it is veined in structure, but this 

 is probably not a constant character. Small grains of magnetite are scattered 

 through the rock, but not so thickly as in many granites. No other ingredients 

 have as yet been detected. Mr. G. W. Hawes has determined the specific 

 gravity at 2.79." 



DISTRIBUTION AND CHARACTERISTICS OF UNAKITE 



Since the publication of Bradley's original note on unakite, in 1874, 

 occurrences of the rock have been noted and described from a number of 

 localities in Virginia and North Carolina. 32 The rock is by no means 



31 F. H. Bradley : Amer. Jour. Sci., 3d ser., vol. vii, 1874, pp. 519-520. 



32 W. C. Phalen : Smithsonian Miscellaneous Collections, vol. 45, 1904, pp. 306-316. 

 Thomas L. Watson : Jour. Geol., vol. xii, 1904, pp. 395-398. 



Watson, Laney, and Merrill : North Carolina Geol. Survey, 1906, pp. 172-174. 

 Thomas L. Watson : Amer. Jour. Sci., vol. xxii, 1906, p. 248. 



Thomas L. Watson : Bull. 426, U. S. Geol. Survey, 1910, pp. 22, 71, 73, 77-78, 111- 

 112, 157-159. 



