NOTE ON AN OCCURRENCE OF GRAPHITIC IRON IN A 



METEORITE. 



By Wirt Tassin. 



AmskoU Curator, DirUion of Mineralogy. 



During the course of some investigations as to the relation of struc- 

 ture to composition in meteoric irons, at present being carried on by me, 

 a bhxck concretion was observed in a sample of the Canyon Diablo 

 meteorite. This concretion was of such a size that it was readily 

 broken out in a nearly perfect condition. 



On cutting it, in order to make a metallographic examination, the 

 mass was found to be a septarian nodule (see figure), the septa con- 

 sisting of the native metals which metallo- 

 graphically did not differ from that of the 

 mass of the iron. The interseptal portions 

 consisted of a very fine-grained, distinctly 

 crystalline graphitic carbon, and amorphous 

 carbon, which could be separated from each 

 other in part by floating. Intimately mixed 

 with the two kinds of carbon is a ver}- tine 

 granular or scaly troilite. There is also 

 present a lustrous metallic, dark steel-gray 

 substance occurring in irregular angular 

 masses varving- in size from minute grains 



.'\ . rr<i • Plan of septarian nodule. 



to one weighing 110 miHlgrams, IhlS ma- (Twice natural size.) 



terial was at first taken for graphite in that 



it closely resembled that mineral. It was, however, strongly magnetic, 



thus afl'ording a ready method for its separation. 



The composition of the material thus isolated is as follows: 

 Fe 88. 84 



^Ti 4.00 



Co («) 



Ki 2.00 



C 4.35 



p 0. 87 



100. 06 

 Specific gravity, 6.910. 



» Present, but not weighable. 



Proceedings U. S. National Museum, Vol. XXXI-No. 1497. 



573 



