50 CORUNDUM^ ITS OCCURRENCE AND DISTRIBUTION. 
Near the head of Muskrat Fork of Shooting Creelc, Chi}^ County, 
N. C, and extending about halfway up the adjoining slope of 
Chunky Gal Mountain, there are two parallel dikes of dark, fine- 
grained hypersthenite, which are from 550 to 600 feet apart, and 
each about 10 feet thick. The dike rock consists of rounded, irregu- 
lar grains of strongly pleochroic hypersthene, nearly half of which 
has been altered to a green amphibole. Corundum occurs in the 
gneiss between these dikes, and also in a band of black biotite, which 
is intimately associated with a small vein of pegmatite 2 feet in 
thickness. The biotite is developed in large scales and plates and 
contains nodules of corundum up to half an inch in diameter, 
wdiich are surrounded by scales of a white mica, muscovite. 
CORUNDUM IN METAMORPHIC ROCKS. 
CORUNDUM IN SERPENTINE. 
At a number of peridotite localities in North Carolina and Georgia 
crystals and fragments of corundum have been found that were 
surrounded by serpentine, but nowhere in the Southern Appalachian 
region has corundum been found associated with the larger masses of 
serpentine that have been derived from the alteration of the peridotites, 
as at several localities in Buncombe County, N. C. In Chester and 
Delaware counties, Pa.,° there is a long belt of serpentine rocks, part of^ 
which, at least, have been derived from peridotite rocks, and in connec- 
tion with these, in the eastern part of Chester County and the Avestern 
part of Delaware County, corundum has been found. In this the 
corundum occurs near the contact of the country rock, and its occur- 
rence in the serpentine is almost identical in conditions with thosf 
of the corundum in the peridotites and pyroxenites of North Caro- 
lina and Georgia. Considerable plagioclase feldspar is associatec 
with the corundum in the vein in a manner somcAvhat similar to th( 
occurrence of this mineral at the Cullakeenee mine. Buck Creek 
Clay County, N. C. 
CORUNDUM IN GNEISS. 
Corundum has been found in North Carolina in the ordinary gneis; 
of the same belt of crystalline rocks in which the peridotites occur 
As observed, these gneisses are often very variable, passing frequently 
into mica-schist and sometimes into quartz-schist. Such transition 
are occasionally quite sudden, but usually there are thin zones of mor 
or less intermediate character; and sometimes it is difficult, if no 
impossible, to decide wdiat should be called gneiss and wdiat mica 
schist, etc. A number of occurrences, part of wdiich may be corun 
« Geol. Survey Pennsylvania, C4, 1883, p. 351. 
