OP ARTS AND SCIENCES. 



59 



Date of Fall or Find. 



No. 



Weight 



in 

 Grams. 



1,217 



15 



Description. 



Etched slab. The Neumann lines 

 appear at first sight like the markings 

 on a chopping-block, without any defi- 

 nite direction, as shown in Fig. 3, 

 which is printed directly from the 

 specimen. A striking feature of the 

 etched surface is the appearance at first 

 of two sets of fine parallel lines, which 

 become obliterated by the continued 

 action of the acid. These lines can be 

 made out near the lower right-hand cor- 

 ner of the figure. The more marked 

 and coarser crystallization, appearing 

 at the left, is unusual in the Coahuila 

 specimens. 



A cleavage mass, broken out from a 

 perfectly compact specimen of the above 

 iron by quick blows of the hammer. 

 This mass, shown of twice its natural 

 size in Fig. 4, has the form of the cube 

 twin described by Tschermak, as typi- 

 cal of the Hauptmannsdorf iron, with 

 this difference, that the cube in this 

 case is modified by the octahedron. 

 On etching the faces, beautiful stria- 

 tions appeared, all parallel to edges 

 either of the cube or octahedron. Most 

 of these lines were so fine as to be mi- 

 croscopic, though a few were coarse 

 enough to exhibit even under a pocket 

 lens all the characters of Widmanstat- 

 tian lines. On the octahedral face 

 there were no regular striations.f 



Another cleavage mass found in con- 

 tact with the previous one, but having 

 the form of an acute rhombic prism 

 with an angle of about 120°. This 

 prism, one etched face of which is shown 

 of twice the natural size in Fig. 5, could 

 only be separated by the hammer over 

 the area abed, and the rest of the face 

 had to be continued by cutting through a 

 very compact part of the specimen, ab, 

 be, and cd are the natural crystal edges. 

 The upper figure was copied directly 

 from the specimen, without any knowl- 



t Oliver W. Huntington "On the Crystalline Structure of Iron Meteorites," 

 Proceedings of the Am. Acad., Vol. XXI. p. 478. American Journal, 3d Series, 

 Vol. XXXII. p. 284. 



