Gentli.] OOb fAngnst 18, 



The corundum closely resembles the coarse crystals which are asso- 

 ciated with mica and feldspar at Ilmensk and the River Barsovka in 

 the Ural. 



The analysis of the broadly foliated muscovite (c 1), that of the 

 albite (c 2). 



d. Very interesting varieties of altered corundum have been discovered 

 by Mr. J. A. D. Stephenson of Statesville, K C, at Belt's Bridge, Iredell 

 county, N. C. The corundum has a gray and grayish-white color, and 

 occurs in masses, sometimes over a foot in diameter, but generally 

 smaller ; they are irregular in form, always more or less rounded, some- 

 times globular, egg-shaped, rarely pyramidal and showing yet the crys- 

 talline form of corundum, but of the original mineral, many of the 

 globular masses do not contain a trace, others contain small particles, 

 disseminated through the mass, or a nucleus in the center. The altered 

 mineral is mostly mica (damourite) some of the specimens also contain 

 black tourmaline in radiating crystalline masses, which sometimes start 

 from the corundum nucleus, but not always. The mica is either compact, 

 of a grayish-white color or subfibrous (analysis (dl) by Miss Mary T. 

 Lewis, after deducting 3.51 of corundum), and very fine scaly with pearly 

 lustre, the scales rarely assume a size of more than 2'"™ in diameter. In 

 one of the specimens in which all the corundum has disappeared, I no- 

 ticed minute cavities, containing fragments of a vitreous mineral which 



' appears to be quartz, but the quantity was too small for further examina- 

 tion. 



In connection with this, I will mention a specimen from the same lo- 

 cality, received by Col. Joseph Willcox. It appears to be a fragment of an 

 irregular hexagonal prism, a little over 100'°"' high, and somewhat less 

 broad. The original form is scarcely perceptible, the sides being rounded 

 and rough. There is a core of unaltered gray corundum of C5 X 55™"" 

 surrounded with subfibrous, and on the outside with scaly mica, inclosing 

 bunches of radiating, black tourmaline ; disseminated through the im- 

 altered corundum are many rounded masses of a brownish-red garnet 

 fro:ii 4 to 6™'" in diameter, an association which I never before have 

 observed. The analysis of the subfibrous mica, surrounding this corun- 

 dum, which has been made by Mr. Frank Prince shows that a portion 

 of the alkalies has been replaced by lime (d3). 



e. In 1876 corundum was discovered in the micaceous schists near 

 Bradford, Coosa county, Alabama, of which numerous specimens have 

 been kindly presented to me by Dr. Eugene A. Smith, State Geologist of 

 Alabama. 



It is usually found in hexagonal prisms, but also in ijyramidal form, 

 apparently 1-2, always, however, very rough and altered. 



The corundum itself is of a brown and bronze color ; sometimes ex- 

 hibiting a star of six rays. Amongst the large number of specimens which 

 I have examined, I have never seen one which was free from an admix- 



