36 MEMOIRS NATIONAL ACADEMY OF SCIENCES, VOL. XIII. 



found some black particles of chromrte in the center of a troilite nodule; with also, perhaps, a 

 trace of cohenite. 



BIBLIOGRAPHY. 

 1. 1902: WARD. Proc. Rochester Acad. Sci., vol. 4, pp. 82 and following. 



Arizona, 1851. See Tucson. 

 Arizona, 1891. See Canyon Diablo. 



ARLINGTON. 



Sibley County, Minnesota. 



Latitude 44 3(X N., longitude 93 56' W. 



Iron. Medium octahedrite (Om) of Brezina. 



Found 1894; described 1896. 



Weight, 9 kgs. (19J Ibs.). 



This meteorite has been described wholly by Winchell, 1 as follows: 



This iron was found on the farm of Jos. Barry, si., 2.5 miles northeast of Arlington, in Sibley County, Minnesota, 

 in March, 1894. It was from the first suspected of being meteoric, but was not examined with care until the spring of 

 1896. A small piece having been broken off and submitted to Mr. Buck, of Arlington, it was forwarded to the writer 

 for examination, after which the whole specimen was procured for the museum of the state university, where it is now 

 preserved. The weight of the entire piece was 19.75 pounds. The following statement was given by W. J. McLeod, 

 Esq., son-in-law of Mr. Barry: 



"Found in Sibley County, Minnesota, on the farm of Joseph Barry, sr., 2.5 miles northeast of Arlington, in March, 

 1894. As it was found on a field that had long previously been cultivated, in the rich black soil and far from any high- 

 way, in a level country free from tone, it is confidently believed by the owners to be a meteor, and the boy who 

 found it, Joe Barry, jr., expects it has some value as a curiosity." 



Four and one-half pounds were broken by a sledge hammer from one corner, previous to which it was somewhat 

 heart-shaped. The missing prong from this break was a precise counterpart in shape to the remaining one. 



A figure, reduced to one-third the natural size, shows the shape of this iron, and the average thickness is about 

 0.5 inch. The upper (convex) surface is tolerably smooth, but has an indistinct, pock-marked aspect, due appar- 

 ently to an internal crystalline structure, or to variation in the relative amounts of the ingredients. The lower surface 

 which is about a plane, is, however, curiously pitted and rough. Some of the pits are so deep as to nearly pierce the 

 specimen. They are smooth, and conico-thimble shaped. This surface has, moreover, a thin scale, or rust, which 

 suggests a meteoric crust. This scale is best preserved in the depressions. The general appearance of the whole 

 piece is that of a refuse piece of iron from a furnace. 



On polishing a small portion of the upper surface and applying dilute nitric acid for a short time, the character- 

 istic crystalline structure becomes beautifully expressed. 



Throughout the etched surface sharp ridges stand up, thus outlining the coarse Widmanstatten structure. These 

 elevations consist of some composition different from the depressions between them, for they not only resist the acid 

 but they do not show the bright iron reflections that prevail in the depressions. These ridges are not entirely persistent 

 and continuous, but disappear suddenly and rise again. 



Between these long ridges the surface has, after etching, a brilliant metallic iron luster, which is due to the reflection 

 of light from crystalline lamellse. These lamellae are apparently cleavages that are in the Widmanstatten bands, and 

 they stand at different angles in different bands. They show that the bands themselves are crystalline throughout 

 their substance. For instance, when placed in the direct sunlight the position at which some of the lamellse are most 

 illuminated by reflections is about45 different from that in which the rest of the long lamellse are illuminated. Another 

 system of coarse lamellae in like manner consists of two series. The broader upper band reflects light in a position 

 at an angle of 90 from that at which the rest of the associated lamellse reflect it. The same fact is observable in 

 other parts of the etched surface. 



These fine lamellse, however, which might be called cleavages, and which characterize the metallic depressions, 

 are crossed by a fine striation wholly independent of the long Widmanstatten structure. In most of these metallic 

 surfaces this striation runs in the same direction, but in some of the bands it is at a different angle with the grand 

 structure. This striation, in like manner, consists of dark ridges separating metallic grooves. They seem to differ 

 from the coarse structure only in being much finer. Thus this iron has not only a coarse Widmanstatten crystallization, 

 each band being, as it were, an individual crystal, but it has what might be considered a fine cleavage and a minute 

 internal structure, which, throughout the separate crystals, maintains its direction and individuality. 



These finer markings suggest those described byj. Lawrence Smith and named Laphainite marks, but they seem 

 to differ from them in an important manner, if they be compared with the description published by Smith, yet there 

 is no doubt that they both are due to a fine internal structure of the iron itself. The reflecting cleavages do not indicate 



