1886.] NATURAL SCIENCES OF PHILADELPHIA. 355 



ON SCHORLOMITE AS A VARIETY OF MELANITE. 

 BY GEO. A. KOENIG, PH. D. 



On the basis of a titanium Melanite from a new locality in 

 Southwestern Colorado, the hypothesis is proposed that Schor- 

 lomite from Magnet Cove, Arkansas, may be considered as a 

 Melanite in which Titanium replaces both Silicon and Aluminum. 

 By a series of analyses of Schorlomite and Melanite, it is pro- 

 posed to establish the above hjqoothesis beyond doubt. The 

 following results are merely given as preliminary information. 



The material from Colorado, obtained through Moritz Stockder, 

 Mining Engineer at Lake City, shows the Melanite as black 

 masses imbedded in a greenish yellow, fine granular matrix, with 

 undefined boundaries. No crystal planes were observed. The 

 color is deep black, brownish at thin edges, and in thin plates. 

 It has an uneven fracture, rather resinous lustre. Sp. gr. = 3" 689. 



Thin sections under microscope show the homogeneous charac- 

 ter and optical indiflerence of the substance. 



B. B. several splinters fused at 3 with slight formation of 

 bubbles (CO^). Hydrochloric acid decomposes the mineral very 

 slowly. The analysis gave in two determinations : 



Si02 =30-n 



Ti02 = 8-11 



APO^ = 2-26 



Fe^O^ = 22-67 



CaO =34-29 



MgO = 0-304 



C02 = 1-48 (loss by fusion). 



9982 



0'5 gr. decomposed in sealed tube required 2*2 cc. of per- 

 manganate (titre = 0-0058 Fe). TiO^ + APO^ were separated 

 from Fe^O^ by (NH^'S in tartaric solution, and APO^ from TiO^ 

 by acetic acid according to Gooch. 



Assuming that Ti replaces Si the ratio is obtained (Si, Ti)02 : 

 (Fe, Al)203 : CaO = S-T28 : 1 : 3-49. But assuming that Ti re- 

 places the sesquioxides in part as Ti^O' under the hypothesis that 

 the permanganate was reduced by Ti-0^ we obtain 3*28 Ti-0^ as 

 replacing alumina = 3*64 TiO'^ It having been ascertained that 



