50 F. A. Genth — Contributions to Mineralogy. 



a. 



Loss by ignition 5-56 



Si0 2 _ 33-38 



A1 2 3 46-49 



Fe 2 3 1-43 



CaO - 6-02 



Na 2 2-47 



K 2 2-33 



Corundum 1.70 



b. 



5.40 



35.79 



45.95 



1-03 



5-49 



2.27- 



2-82 



2-07 



99-38 100-82 



The analyses indicate a mixture of several micas, margarite 

 predominating. 



Chloritoid. — This mineral which has been so frequently ob- 

 served with corundum, as at Mramorskoi in the Ural, at 

 Gumugh Dagh in Asia Minor and elsewhere, is also found with 

 the corundum of Bull Mountain. In the bladed cyanite it is 

 found in small quantity, but in the rhaetizite, associated with 

 muscovite it surrounds a nucleus of blue corundum, from 

 which it originated. 



The foliated masses have a blackish green color, the largest 

 is 30 ram in diameter. The sp. gr. I found = 3*614. My anal- 

 yses gave : 



]. 2. 



Loss by ignition 6-64 6'58 



Si0 2 25-03 25-53 



A1 2 3 39-75 39-23 



FeO 22-92 



MnO ._ 1-30 1-14 



MgO 3-32 3-32 



CaO__ 0*21 



Na 2 0.07 



K 2 . 0-07 



99*31 

 The pure mineral contains no ferric oxide. 



A short distance from the locality where these minerals have 

 been found, indications of the occurrence of the same species 

 have been observed in several places. 



This occurrence of corundum is entirely different from any 

 previously described. 



Some specimens of blue corundum in grayish brown rhaeti- 

 zite, discovered several years ago by Mr. J. A. D. Stephenson, 

 of Statesville, N. C, at Hunting Creek, north of States ville 

 are very similar ; there was also a mass, consisting of crystals 

 of andalusite, altered into a micaceous mineral which, however, 

 was not further investigated. 



Chemical Laboratory, jt 



111 & 10th St., Philadelphia, November 16, 1889. J 



