100 MEMOIRS NATIONAL ACADEMY OF SCIENCES, VOL. XIII. 



The possibility of a terrestrial origin of the Canyon Diablo meteorites was also discussed by 

 Huntington 14 with the conclusion that such an origin is disproved by an examination of the 

 exterior surface of a mass weighing 1,087 pounds in the Harvard Museum. He says: 



It is a roughly spherical mass somewhat flattened in one plane. One of these flattened surfaces shows signs of 

 fusion, with deep pittings almost like bullet holes, but larger on the interior than at the orifice. Occasionally, they 

 are meeting, but all preserve the same general direction. They vary from ^ to 2 inches in diameter and reach in some 

 cases a depth of 3 or 4 inches. These can not be explained by unequal heating or by the erosive action of the air, since 

 they are larger on the interior than at the surface. The other side of the mass shows large concave surfaces, as if pieces 

 of 6 or 7 inches in diameter had flaked off, or the hollows had been scooped out by the action of pneumatic drills. 



For some time these two utterly different surfaces were a puzzle, but a closer examination disclosed troilite in 

 the depths of some of the small cavities, while in the side of the larger pittings the same mineral appears exposed but 

 unaltered. Evidently, then, this mass must have been a meteorite, moving with its smoother face to the front, and 

 perhaps revolving. In such a case the front would acquire the melted appearance observed, and the troilite nodules 

 would at once fuse and become dissipated, leaving the deep and erratic cavities so characteristic of this iron, while 

 the portion in the rear would acquire the well-known pittings due to the flaking off of irregular portions. The iron 

 is largely filled with troilite nodules, and that they did not subsequently weather away is evident from the fact that 

 these cavities appear only on the front of the mass. 



The etched surface shows great variation in the distribution of the Widmannstatten figures and troilite nodules, 

 and the occurrence of diamond evidently varies likewise. 



Cohen remarks : 15 



It ia not yet certain whether the Canon Diablo iron is meteoric or, like the Greenland nickel-iron, of terrestrial 

 origin; in common with the latter it has a very low percentage of nickel, at least in portions of it, and a comparatively 

 high percentage of carbon. 



Derby 16 investigated a Canyon Diablo specimen as to its constituents and obtained results 

 as follows: 



A specimen of the Canon Diablo meteorite, obtained from Mr. E. E. Howell, of Washington, and stated to be one 

 of the original lot brought from Arizona by Dr. A. E. Foote, was treated by the fractional method of Prof. E. Cohen 

 by Dr. G. Florence, with the following results: 



The specimen, weighing nearly 200 grams, was a perfect meteoric individual, presenting no fractural surfaces, but 

 everywhere the rough pitted surfaces of meteoric masses. In appearance it suggested a metallic bleb, broken or 

 weathered out of friable, or more easily decomposable material. An examination of a considerable number of speci- 

 mens of all sizes in Mr. Howell's collection shows this to be a general characteristic of the Canon Diablo group. Nothing 

 in the shape and aspect of the masses suggests the occurrence of planes of slight cohesion (presumed to be the limits of 

 crystalline individuals described as Wollaston planes in the Bendego mass) and which, by facilitating fracture, either 

 in the original place of formation, or in the act of falling, have probably produced the approximately plane faces and 

 angular edges that characterize that meteorite. Such faces and edges might be expected on the Canon Diablo mass, 

 which seems to be required by the conditions under which they were formed. A rough, jagged, and pitted surface is, 

 however, common to all of them, showing a perfect individualization and suggesting on a large scale, the small, irregular 

 metallic masses scattered through the stony matrix of a mesosiderite. Referring them to a single original mass, the 

 hypothesis may be ventured that on its arrival in our atmosphere this was not homogenous but consisted of a large 

 mesosiderite with unusually large metallic nodules of that became separated by the explosions attending the fall, and 

 probably also by subsequent decay and disaggregation of the stony matrix. 



After freeing the specimen as far as possible from its rust crusts by scraping after soaking in strong acid , it was treated 

 with cold hydrochloric acid of a strength of 1 to 10. The solution was effected slowly with evolution of gas and a sepa- 

 ration of a variety of grains with a metallic aspect and of a light black residue resembling coal dust. A veinlike mass 

 some 3 mm. thick, that showed through the rust crust with the appearance of the pencillike incusions of troilite in the 

 Bendego meteorite, extended for about a centimeter into the mass, and, not being acted upon by the acid, came away 

 in fragments. After 14 weeks of treatment with frequent changes of acid the action almost ceased, although a 

 considerable mass remained still undissolved. This had much the shape and appearance of the original meteorite 

 though much more irregular and jagged, and represents a nucleal portion less soluble than the generality of the mass. 



The undissolved residue was separated by screening through fine bolting cloth, sorting under the lens, and with a 

 magnetized knife point, into the following groups: Vein matter consisting of massive schreibersite with cohenite; 

 irregular jagged fragments resembling the larger nucleal piece and bristling with needles of rhabdite (zackige Stiiclce 

 of Cohen?); tsenite; coarse schreibersite and cohenite from the general mass and not from the vein (a considerable part 

 of the schreibersite was free but the grains of cohenite were so charged with it that no satisfactory separation of the two 

 could be effected); fine magnetic residue, for the most part schreibersite in the form of rhabdite needles but with fine 

 particles of tsenite ; granular schreibersite and cohenite, and a black coal-dust-like residue highly charged with rhabdite. 

 The separation could not be completely made except for the jagged pieces and the coarser tsenite, schreibersite, and 

 cohenite. In the finer material the two last were so lumped together that neither by sorting nor by gravity or magnetic 



