18 Journal, of the Mitchell Society [June 



corundum a little muscovite is developed. This has been ob- 

 served on corundum from other localities. 



Corundum in Pyroxenite : — At many of the corundum-bear- 

 ing peridotite localities in ISTorth Carolina, such as those of 

 Macon, Jackson, and Transylvania counties, a pyroxenite com- 

 posed of interlocking, coarse-bladed, gray enstatite constitutes 

 an important part of the outcrop; and at a number of places 

 the pyroxenite alone forms oval and lenticular masses in every 

 way similar to those composed of peridotite. In both cases cor- 

 undum-bearing zones of secondary minerals are frequently 

 formed along the borders of the pyroxenite and intersect the 

 mass of the rock in exactly the same manner as described above 

 for peridotite. Enstatite rocks are somewhat common in l^orth 

 Carolina, but accessory minerals in them are rare, and the most 

 common one observed is chromite, in small grains. In a few 

 instances corundum has been found in them. 



Corundum in Amphiholite : — Associated with the peridotite 

 rocks of Clay County, IST. C, and of the adjoining Towns 

 County, Ga., are dikes of amphiholite, which are for the most 

 part between the peridotite and the gneiss, although in some 

 places they cut the peridotite formation close to the contact of 

 that rock with the gneiss. These dikes vary in width from 25 

 to over 300 feet, their average width being from 75 to 100 feet. 



Corundum in Anorthosite : — The amphibole, with its pre- 

 vailing light-green amphibole and small amount of feldspar, 

 that so frequently accompanies and intersects the peridotites of 

 Clay County, IST. C, and of Towns County, Ga., becomes in 

 places highly feldspathic, and by the dwindling and disappear- 

 ance of the amphibole it passes into the anorthosite facies at 

 several localities. 



Anorthosites of this character, with more or less corundum 

 in grains and irregular masses distributed through the rock, are 

 found on the western slopes of Chunky Gal Mountain, Clay 

 County, ]^. C, and in association with some of the amphibolites 

 of the Buck Creek area in the same county. These rocks are 

 always greatly subordinate in quantity to the associated amphi- 



