154 COKUNDUM, ITS OCCUERENCE AND DISTRIBUTION. 
carry the corundum. The corundum varies from a deep pur])lish 
brown to a dark greenish gray, and is in irreguhir nodules Aarying 
from a quarter of an inch to an inch in diameter and in elongated 
barrel-shaped crystals sometimes an inch long. 
There are two and perhaps more of these corundum-bearing bands 
that are parallel to each other, making the total known length of 
corundum-bearing rock over 24 miles. The percentage of corundum 
in the rock is very low, experiments that have been made on samples 
taken at diiferent points on the band shoAving the presence of only 
e>.5 per cent. 
Most of the outcrops of the bands of corundum rock have been 
found in connection Avith gneiss, and lie in lines that are roughly par- 
allel to the strike of the gneiss. Some of them are, hoAvever, in close J 
proximity to a nepheline-syenite. J 
Specimens of corundum sent by Dr. T. L. Walker from a district | 
about 250 miles north of Calcutta and labeled " Pipra, South ReAvah, | 
India," are apparently similar to those described by Holland. The f , 
corundum is very fine grained in appearance and in noduk^s up to 2 '^ 
or more inches long by 1 or more inches broad, Avith a pinkish to | 
purplish-broAvn color. These nodules are partly or completely sur- i j 
rounded by a greenish mica, Avhose folia are small and rather brittle, 
and Avhich has been referred by Mallet « to the euphyllite variety. In 
the mica there are small rough crystals of tourmaline. Just Avhat the 
occurrence of this corundum is I do not knoAv, but from the general 
appearance of the specimens it should make an ore from Avhich the 
corundum could be readily separated and a A^ery clean by-product 
obtained. If the corundum in the rock Avas 10 to 15 per cent of the 
quantity required to be remoA^ed in mining, this should make a A^ery 
important and profitable corundum deposit. 
In other specimens labeled '' Salbanni," 4 miles east-southeast of 
Barampur, Manbhoorn district, India, there are blue crystals of corun- 
dum Avith a rough hexagonal prism embedded in a mass of inter- j 
locking bladed crystals of cyanite. 
It is very probable that nearly all of the corundum deposits that 
are knoAvn in India are secondary minerals and the result of meta- 
morphism. Professor Judd, in his j)aper on the Rubies of Burma 
and associated minerals,'' says that all the corundum-bearing rocks in 
the districts of southern Asia appear to be gneisses Avhich sometimes 
pass into schists and frequently contain masses of limestone and 
dolomite. 
« Mineral India, 1887, p. 180. and Dana's Mineralogy, (Jth ed., 1892, p. 024, 
» Trans. Royal Soc, London, 1896, p. 191. 
