Genth.] d|4 [Sep. 19, 



emerald to grass-green, and passing into grayish-green to greenish-gray. 

 H = 5.5. Sp. Gr. of the grass-green variety = 3.120. 



B. B. it melts easily to a greenish glass, whilst the outer flame is 

 colored yellow. 



A sample of the grass-green mineral, selected with great care and ap- 

 parently//'^ from feldspar, was analyzed by Mr. Thos. M. Chatard, who 

 found : 



Si0 2 = 45.14 contains oxygen 24.07 =2.06 



A1A 17.59 « « 8.20) 8 .45 =0 .72 



Cr 2 3 0-79 " " 0.25) 



FeO 3.45 " " 0.77 -j 



NiO = 0.21 " " 0.04 I 



MgO 16.69 " " 6.68 [ 



CaO = 12.51 " " 3.57 



Na 2 = 2.25 " " 0.58 



K 2 = 0.36 " " 0.06 J 



Ignition = 1.34 



= 11.7 



100.33 



This gives very nearly the atomic ratio of RO* : R 2 3 : SiO„ = 1 : 

 0.25 : 1 = 4 : 1 : 4, corresponding to the formula : 4RO, 3Si0 2 + 

 R,0 3 , Si0 2 . 



It will be observed that this agrees exactly with the composition of 

 Kokscharoffite, and that it has no resemblence to arfvedsonite, with 

 which it has been placed by C. U. Shepard (loc. cit.) as chromarfvedson- 

 ite. At some corundum localities we find that other varieties of amphi- 

 bole are associated with corundum, or even penetrate into the mass of 

 the same. 



A black or brownish-black hornblende frequently occurs in the ande- 

 site of Cullakenee, Clay County, North Carolina, and a dark green 

 almost black variety, resembling actinolite is found, often associated 

 with zoisite, with and in the corundum of the same locality ; also with 

 the corundum at Shooting Creek in the same County, and rarely at the 



Culsagee Mine. 



9. Zoisite. 



In the Ural, at Mramorsk, zoisite has been observed by G-. Rose (loc. 

 cit.) as an associate of corundum. B. Sillimanf described it under the 

 name unionite as occurring in company with corundum, tourmaline and 

 euphyllite at Unionville, Pennsylvania, but the best locality of it is the 

 Cullakenee Mine, in Clay County, North Carolina. Here it occurs in 

 crystals, but usually in compact columnar and easily cleavable masses. 

 Its color is from grayish to greenish and brownish-white. Many of the 

 specimens show distinctly that it is the result of the alteration of corun- 

 dum. The pink corundum is often surrounded by a thin coating of 



•Including R O in this and all subsequent analyses. 



t B. Silliman 2] VIII, 384. 



