128 MEMOIES NATIONAL ACADEMY OF SCIENCES, VOL. XIII. 



Meunier 4 described 'the structure of the iron as follows: 



The kamacite is in bands, very rich in Neumann lines, and limited by the very thin leaves of tsenite. The plessite 

 is normally abundant and in some places black inclusions of several millimeters diameter are visible. Dissolving in 

 acid produces a little hydrogen sulphide and liberates the scanty laminae of schreibersite. 



Cohen 5 remarked that Reichenbach lamellae were very numerous and beautiful in this 

 meteorite. 



Kunz 3 suggested that Cleveland was of the same fall as Dalton, q. v. 



The iron is chiefly preserved in the Museum of the Academy of Sciences of Philadelphia. 



BIBLIOGRAPHY. 



1. 1866: SHEPARD. Amer. Journ. Sci., 2d ser., vol.42, p. 251. 



2. 1886: GENTH. Proc. Acad. Nat. Sci. Philadelphia, pp. 366-368. 



3. 1887: KUNZ. Amer. Journ. Sci., 3d ser., vol. 34, pp. 473^475. 



4. 1893: MEUNIER. Revision des fers m6t6oriques, pp. 52 and 58-59. 



5. 1894. COHEN. Meteoritenkunde, p. 193. 



COAHUILA. 



State of Coahuila, Mexico. 



Latitude 28 42' N., longitude 102 51' W. (Fletcher). 

 Iron. Hexahedrite (H); Coahuilite, type 4 of Meunier. 

 Known since 1837; described 1855. 



Weight many thousands of pounds. The Butcher irons consist of 8 masses weighing 654, 580. 550, 438, 430, 

 404, 353, and 290 pounds; total, 3,699 pounds (1,678 kg.). 



The history of this puzzling group of meteorites has been given by Cohen, 53 as follows: 



From the Mexican States, Nuevo Leon and Coahuila, and especially from the territory known as the Desert of 

 Mapimi, lying partly in Coahuila and partly in Chihuahua, as well as from the neighboring portion of Texas, numer- 

 ous hexahedrites have been, under different names, in part carefully described and in part briefly mentioned. 

 With the question whether all these hexahedrites belong to one fall or many, Smith, Burkart, Huntington, Fletcher, 

 and Brezina have occupied themselves. Smith, 14 in 1871, was of the opinion that all the irons found on the Desert 

 of Mapimi, within a radius of 500 miles, belonged to one great fall. He included among these not only the hexahe- 

 drites of Saltillo and the Butcher irons but also the octahedrites Morito and Adargas. Burkart " considered it prob- 

 able that Saltillo, Bonanza, and the Butcher irons might belong to one fall which took place in 1837 in the region of 

 Santa Rosa, but left the question open. Huntington, 82 in 1887, came to the conclusion that the Coahuila irons of the 

 Sanchez Estate and Fort Duncan could not be separate, since their specific gravity, composition, etching figures, and 

 other properties showed no differences, but he included the octahedrites of Morito and Adargas in the Coahuila iron. 

 Two years later he 3S changed his view, since he observed in the Butcher irons cleavage different from that of Sanchez 

 Estate and Fort Duncan, while that of the latter corresponded with that of Scottsville and Holland's Store, and regarded 

 this as proof that two different falls occurred; the one furnishing the Butcher iron, the other the remaining four irons. 

 From this he came to the conclusion that one meteor which passed over the North American continent let fall masses 

 at widely separated points. These views have not been shared by other investigators. Fletcher's investigations ** 

 were of special importance since he collected all the literature and studied it critically. He concluded that before 

 the introduction of railways transportation of heavy masses from the coast to the interior was difficult and expensive, 

 and hence a distribution of iron masses for use as anvils could have taken place. Such distribution had often been 

 proved and hence seemed probable even where no direct proof existed; also the belief that such masses might contain 

 precious metals would also often cause their distribution. Fletcher describes the way in which different masses 

 might have been transported. Since all the irons were hexahedrites he hardly thought it possible that two falls of 

 the same type could have occurred in a relatively limited area. His conclusioiiif'tFas that all the above-mentioned 

 irons belonged to one fall and the fall took place in a limited area. Later, Fletcher modified his view in so far as Fort 

 Duncan was concerned, since in the catalogue of the London collection he gives this iron a separate locality with 

 the remark that it may have come from the same region as the Coahuila iron. Brezina 47 thought, on the other hand, 

 that two separate falls took place, since some of the irons are distinguished by a high content of rhabdite and (prob- 

 ably on account of this) are attacked with difficulty by acids. One locality he designates as Fort Duncan and includes 

 with it Sanchez Estate and the so-called Smithsonian iron. To the other locality, Coahuila, he ascribed all the other 

 irons. For the present, I follow Brezina's conclusions, although his arguments are no more convincing than those of 

 Fletcher. On the one hand the fall of two masses of hexahedrites at no great distance from one another is not very 

 probable but not impossible; on the other hand we know little regarding the relations of the single masses of an iron 

 shower. The greatest number of different masses in such a case have been investigated in Toluca, and these are all 

 octahedrites of medium width though all show some differences in their intimate structure; of Canyon Diablo some 

 pieces are rich in cohenite, some almost free; of Babb's Mill, there are two masses which seem to belong together 

 through similarity of structure, but their chemical composition is very different. 



