48 F. A. Genih — Attributions to Mineralogy. 



ated rocks and minerals, andalusite, cyanite, chloritoid, mica, 

 etc., all of which were collected on the surface of not over six 

 acres of ground on the side of a hill, 1,800 to 1,900 feet above 

 the level of the sea. Its continuation leads to a mountain 

 about 3,000 feet in height and is the outlying knob of Bull 

 Mountain, being connected with the latter by a high ridge. 

 Bull Mountain runs parallel with the Blue Ridge and is about 

 as high. The knob mentioned above is between 1-J- to 2 miles 

 from Stuart. 



The rocks of Bull Mountain are mostly mica schists, so- 

 called talco-mica schists, chloritic schists and slates, resembling 

 roofing slate (not over two miles from Stuart). Some of the 

 talco-mica schists near the corundum resemble gneiss and are 

 highly garnetiferous and in places contain crystals of mag- 

 netite ; then again, on a ridge near by, they are full of crystals 

 of staurolite. No serpentine or chrysolite rocks have been 

 observed in connection with the corundum. These rocks are 

 intersected by several granite dikes and the corundum and its 

 associated minerals are found on the surface, generally between 

 the outcrops of the dikes, and probably belong to them. 



Corundum. — Only a small quantity of corundum has been 

 found ; the largest piece which I have seen is 25 mm in diameter. 

 All tile crystals and crystalline masses appear to be remnants 

 of the alteration of larger masses, into other minerals. Some 

 of the crystals are hexagonal prisms, or, tapering at the ends, 

 perhaps very acute pyramids with the basal plane ; mostly they 

 cluster together and form rounded masses, much intermixed 

 with mica ; on breaking they show the characteristic striation 

 and, occasionally, are asteriated. Their color is mostly deep 

 blue, sometimes intermixed with white, grayish and brownish 

 white. Sometimes only microscopic grains are left, dissemi- 

 nated in the materials, resulting from the alteration of the co- 

 rundum, viz : andalusite, cyanite, mica and chloritoid. 



Andalusite. — The alteration of corundum into andalusite 

 has never been observed before. Only a very small portion of 

 the andalusite still exists unaltered. The andalusite crystals 

 very closely resemble those from Lisenz in Tyrol, but only a 

 few pieces show the common prism and basal plane. Color 

 grayish and reddish white to flesh- red. The best crystal is 

 nearly 40 mm long and 20 mm thick and is coated with a thin film 

 of muscovite ; other masses, the largest about 80 mm in length, 

 are largely mixed with muscovite and cyanite, and, occasionally, 

 enclose some quartz. 



The analyses of the purest, carefully picked out with the aid 

 of a good lens have been made, of the grayish white variety 

 by me (1) and of the reddish white by Mr. James S. de 

 Benneville (2 and 3) : 



