HUNTINGTON. — SMITHVILLE METEORIC IRON. 255 



of the Sinithville iron in hydrochloric acid, assisted by a battery,* a 

 black residue was obtained, consisting mainly of small graphitic crys- 

 tals, with a predominence of cubo-octahedral forms, but showing also 

 perfect little cubes without any modifications, and others with their 

 edges truncated by the dodecahedron, and occasionally bevelled by a 

 very obtuse tetrakis hexahedron. This was evidently the now well 

 known form of meteoric graphite, first seen by Haidinger in the Arva 

 iron,f named Cliftonite by Fletcher in the Youndegin iron, X but also 

 found by him in the Cocke County iron. 



While examining a nodule of graphite formerly obtained by J. 

 Lawrence Smith from the Sevier County iron, it was accidentally 

 broken and showed in its interior what appeared to be a skeleton 

 octahedron of graphite three eighths of an inch in diameter, and with 

 all but one of its faces sufficiently perfect for measurement by an 

 application goniometer. This striking feature at once suggests that 

 this also may be a pseudomorph after diamond. 



With the Cliftouite from the Sinithville iron were to be seen 

 numerous white glassy grains. On digesting the residue for a long 

 time with hydrofluoric acid, most of the white grains disappeared, 

 but a few remained entirely unaffected by the acid. These appeared 

 as very brilliant transparent angular fragments, and exhibited a hard- 

 ness sufficient to scratch the ruby. As only a few grains were obtained 

 from the amount of iron placed at the disposal of the writer, no further 

 experiments could be made, but in all probability the grains were 

 diamond. 



In a letter from Professor Ward dated October 13, 1893, he says, 

 " The ' Smithville ' seems to cut harder than any iron which we have 

 yet undertaken " ; and Fletcher says of the Youndegin iron, " The 

 large specimen was cut on the premises of the Museum by means 

 of hack-saws, and was found to be so hard that three weeks were re- 

 quired for the severance of a fragment of which the cut face is not 

 two aud a half inches square." § May not this unusual hardness be 

 accounted for by the presence of minute diamonds? 



In view of the constant occurrence of graphite in meteoric iron, and 

 the frequent appearance of the same in the crystalline form of diamond, 

 (the carbonaceous material apparently varying in hardness from one 



* These Proceedings, Vol. XXIX. p. 204. 

 t Pogg. Annalen, Bd. LXVII. p. 437, 1846. 

 } Mineralogical Magazine, Vol. VII. p. 121, 1887. 

 § Ibid., p, 123. 



