10 MEMOIRS NATIONAL ACADEMY OF SCIENCES. ivol. xtv. 



The Buff's Mountain, South Carolina, meteoric iron, and its included phosphide. — This 

 beautiful iron was first described by Shepard • and has since been the subject of numerous other 

 notices, which need reference here only as they bear directly upon the matter in hand. An etched 

 surface shows it to be a medium octahedrite, after Brezina, or a caillite if we follow Meunier. 

 It is chiefly distinguished by the broad fields of plessite and the lack of notable quantities of 

 troilite. The kamacite bands are somewhat swoUen and there are occasional rather incon- 

 spicuous Reichenbach lamellae. My attention was first drawn to it by the imsatisfactory 

 nature of Shcpard's analysis and his supposed discovery of potassiimi as one of its constituents. 

 A slice weighing a little over 150 grams was therefore submitted to Dr. J. E. Whitfield with the 

 request that he utilize so much as was necessary for an exhaustive analysis. Bulk analysis 



yields : rer cent. 



Iron 90. 654 



Copper 0.018 



Nickel 8-550 



Phosphorus 0. 233 



Cobalt 0. 500 



Carbon 0.025 



Sulphur 0.020 



Silicon None. 



Total 100. 000 



with no traces of platinimi, palladium, iridium, ruthenium, or the allied elements. Shepard, 

 it may be recalled, reported 96 per cent iron; 3.121 per cent nickel, with chromium, cobalt, 

 magnesium, and sulphur in traces. Later Rammelsburg reported a mean of 8.62 per cent 

 nickel, which is substantially the amount given by Whitfield above. There is nothing of 

 especial note in this composition unless it be its freedom from the rare elements. 



Ninety grams of the iron yielded 1.4843 grams of material insoluble in hydrochloric acid 

 of one-half ordinary strength. This residue when examined under the microscope was found 

 to consist largely of schreibersite particles, among which were a few of sufficiently perfect crys- 

 talline form to permit measurements and determination of crystaUine system. The material 

 possessed the well-known physical properties of schreibersite (see Cohen, Meteoritenkunde, 

 pp. 118-131), including the characteristic habit of breaking up readily into cuboidal forms, 

 and which need not be further discussed. 



The particles showing well-developed crystal faces were submitted to Dr. Edgar T. Wherry, 

 then assistant curator in charge of the Mineral Department, who reported as foUows: ^ 



The crystals average about one-half millimeter in diameter and are irregularly distorted, some of the faces being 

 cavernous; the system of crystallization is not evident on superficial examination. The faces yield, however, fairly 

 good reflections, the positions of which can be located in many cases within 5-10 minutes, unquestionable tetragonal 

 symmetry being exhibited by the angular relations. The forms observed are: c (001) a (100), m (110), o (111), and 

 x(362). In addition there are rounded or poorly developed faces of other pyramids and prisms. All of the forms are 

 incomplete, but there is hardly sufficient regularity in the suppression of faces to justify the assignment of the crystals 

 to any particular hemihedral class. 



Below are given the angles observed, which compare closely with those measured on arti- 

 ficial crystals by Mallard, Hlawatsch, and Spencer. 



Table 1. — Measured and calculated angles of iron phosphide. 

 Tetragonal, c= 0.346 ±0.001. 



1 Amer. Journ. Sci., vol. 10, 1850 p. 128. 



' Amer. Mineralogist, vol. 2, 1917, pp. 80-81; vol. 3, 1198, p. 184. 



