phalen] new occurrence of unakite 307 



components of the adjacent rock and is secondary. Such a peculiar 

 combination of quartz, orthoclase, and epidote should not be uncom- 

 mon in regions of dynamic or static metamorphism where granites 

 or other feldspathic rocks occur, containing the colored micas, 

 pyroxenes, amphiboles, etc. 



The term unakite was applied originally in 1874 by F. H. Bradley,^ 

 who, in the reference cited below, says : 



" This name unakite is proposed for a member of the granitic 

 series from the Great Smoky Mts., a portion of the Unaka range 

 of the Blue Ridge, which range forms the boundary between North 

 Carolina and Tennessee. 



" The specimens thus far seen are from the slopes of the peaks, 

 known as ' The Bluff,' ' Walnut Mt.,' and ' Max's Patch ' in Cocke 

 Co., Tenn., and Madison Co., N. C. The rock is said to occur also 

 in Yancey Co., N. C, but in a comparatively inaccessible region. 



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

 constant replacement of the mica of common granite or the horn- 

 blende 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. The 

 rock is very compact and takes a high polish and will doubtless 

 prove a valuable material for ornamental architecture. 



" The deep weathering of all the rocks of the southern Appala- 

 chians has caused the covering of these slopes with deep beds of 

 debris, which conceal most of the outcrops and the dimensions of 

 the bodies of unakite are therefore, as yet, unknown." 



A perusal of the literature since Bradley's brief description in 

 1874 reveals nothing more than mere allusions to the name and 

 occurrences of the rock.^ It is not mentioned in the latest petro- 

 graphical lexicon of Loewinsson-Lessing, and, so far as the writer is 

 aware, the only reference to the Milams Gap locality is by Merrill.^ 



Mr. F. B. Laney, who spent the last season in a survey of the 

 building stones of North Carolina, informs me that the unakite of 



^ Am. Jour. Science, 3d series, vii, 1874, pp. 519-520. 



^ Dana, Manual of Geology, 4th ed., p. 85. Merrill, Rocks, Rock-weathering 

 and Soils, 1897, P- 68. E. H. Williams, Manual of Lithology, N. Y., 1895, 

 p. 128. Williams also calls attention to the occurrence of unakite in the 

 Fichtelgebirge, Schwarzwald, and the Pyrenees. 



" Stones for Building and Decoration, 1903, p. 86. 



