COKUNDUM IN METAMORPHIC ROCKS. 51 
dum in gneiss, are described under the head of mica-schist; some of 
the rock that Avas at first thought to be a gneiss is now known to be 
a qnartz-schist. 
In the eastern part of Clay County, N. C, on the southern slope of 
Gross Ridge of the Chunky Gal Mountains, just above Thumping 
Creek, corundum has been found in the gneiss at a number of points. 
The rocks are so covered with soil and decomposed rock that the 
exact relation of the corundum-bearing gneiss to the normal gneiss 
can not be determined, but from what can be seen the former appears 
to be in narrow bands cutting through the latter. In structure^ the 
gneiss is distinctly laminated and very fine grained, except the por- 
tions immediately surrounding the corundum, where its constituents 
are nnich more coarsely crystallized, especially the biotite. It is a 
hornblende-gneiss, showing but little mica except where associated 
with the corundum. 
The corundum occurs in nodules and crystals, half an inch and 
smaller in diameter, sometimes wrapped with muscovite in a manner 
similar to that described for the corundum in the chlorite-schists 
(p. 59). The crystals are prismatic, with the length of the prism 
usually two or three times its diameter. Occasionally they are very 
flat, with the j^rism not over a quarter of an inch in length and half 
an inch in diameter, and from their appearance these crystals are 
known locally as " button " corundum. 
The occurrence of corundum in the gneisses of Clay County is illus- 
trated in PL III, B, from a photograph of a mass of gneiss con- 
taining corundum from the Meminger and Hooker mine, Muskrat 
Fork, Clay County. 
In Buncombe County, N. C, on the Elk Mountain range, a few 
miles north of Asheville, corundum has been found associated Avitli 
garnet, sometimes being entirely inclosed by the garnet and at other's 
inclosing the garnet. The corundum occurs in a garnetiferous gneiss, 
and although it is somewhat abundant it is very doubtful if this will 
prove to be a commercial source of corundum. As described by Mr. 
C. E. Lyman, of Asheville, the corundum is found in crystals that 
sometimes measure as much as an inch in diameter. They are pris- 
matic and are terminated by the basal plane. They vary consider- 
jably in color, from blue to red, and a few gems have been cut from 
isome of them. The corundum is found in the gneiss near its contact 
iwith a pegmatitic dike. 
In Jackson Count}^, N. C, just north of Betts Gap, in the Cowee 
Mountains, splendid grayish, translucent crystals of corundum have 
been found in a garnetiferous gneiss. On Caney Fork of Tuckasegee 
[River, elackson County, at the mouth of Chastains Creek, and also 
^t a point 2 miles up Chastains Creek, corundum surrounded by 
muscovite is found in small grains and nodules up to an inch in 
