248 T. L. Watson — Occurrence of Unakite. 



Art. XXIII. — Occurrence of TJnakite in a New Locality in 

 Virginia / by Thomas L. Watson. 



The name unakite was proposed for a unique variety, of 

 granite composed of the essential minerals epidote, pink feld- 

 spar and quartz, from the Great Smoky Mountains, a portion 

 of the Unaka range of the Blue Ridge, which marks the bound- 

 ary between Tennessee and North Carolina. The type local- 

 ity, Madison county, .North Carolina, and Cocke county, 

 Tennessee, was first described by Bradley in 1874,* and the 

 specimens were from the slopes of the peaks known as " The 

 Bluff," "Walnut Mountain," and " Max's Patch," Cocke 

 county, Tennessee, and Madison county, North Carolina. , 



Later, a second locality in which this rare variety of granite 

 occurs was noted in the Blue Hidge at Milam's Gap, near 

 Luray in Page and Madison counties, Virginia. Phalenf 

 visited and studied the unakite in the Virginia area and, in 

 1904, published a preliminary paper on the occurrence and 

 petrography of the unakite and its associated rock. 



The occurrence of the unakite in the two widely separated 

 areas is somewhat similar, but the unakite-bearing rock is dif- 

 ferent in each locality. In the North Carolina-Tennessee 

 area the unakite-bearing rock is an epidote-bearing mica gran- 

 ite which, in places, contains little or no quartz and becomes 

 syenitic.J The unakite-bearing rock in the Milam's Gap area 

 of Virginia is reported by Phalen to be a hypersthene akerite. 

 In both localities the epidote of the unakite has been proved 

 by Watson and Phalen to be secondary.§ 



In a recent trip to Ashe county, North Carolina, the writer 

 collected specimens of typical unakite from Grayson county, 

 Virginia, a locality not hitherto reported, so far as the writer is 

 aware. Specimens were collected along the Marion-Jefferson 

 public road, about two and a half miles south of Troutdale, a 

 railroad terminus near the crest of Iron Mountain, in Grayson 

 county, Virginia. Time was insufficient to prove the extent 

 of the area or to study the occurrence and association of the 

 rock. Loose angular masses of moderate size of the unakite were 

 observed for some distance along the roadside and the speci- 

 mens taken closely resemble those from Madison county, 

 North Carolina. The rock (unakite) is composed of dominant 

 yellow-green epidote, deep pink feldspar and quartz, with no 

 trace of a ferromagnesian silicate indicated. 



*This Journal, vol. cvii, pp. 519-520, 1874. 



f Smithsonian Miscellaneous Collections, vol. xlv, pp. 306-316, 1904. 

 X ; Watson, Thomas L., Journal of Geology, vol. xii, p. 395 et seq., 1904. 

 § Loc. cit. 



Geological Department, Virginia Polytechnic Institute, 

 Blacksburg, Virginia, June, 1906. 



