METEORITES OF NORTH AMERICA. 87 



Smith 2 gave the following analysis : 



Fe Ni Co Cu P 



89.12 10.02 0.26 0.01 0.12 =99.53 

 Specific gravity, 7.72. 



Brezina 3 , 4 gave a detailed account of the structure of this iron as follows: 



A fragment weighing 1 kg., 334 grams, has three etched section surfaces almost perpendicular to one another and 

 one unetched section surface parallel to one of the former; as for the rest, the fragment is bounded by the natural outer 

 surface, which is constituted like all meteorites which have lain for a long time in the ground. 



Upon the etched surface it appears above all that the principal part of the iron has an apparently perfectly compact 

 structure; in this ground of a lusterless iron-gray color lie numerous lamellae, sometimes entirely individual, sometimes 

 massed together in juxtaposition but not heaped up like scales, upon each section of which appear four differently 

 arranged systems; these lamellae taken together form a framework, and indeed, an octahedral framework exactly as 

 indicated (by Tschermak ) for an hexahedral form. The groundmass is entirely lusterless and structureless; a peculiar 

 shimmering appearance of the same is produced by inclusions to be mentioned later on; the hardness of the groundmass 

 is unusually low, something under 4, which is easily scratched by fluorite, and by scratching with a steel needle the 

 difference in the same respect is likewise ascertainable. The systems of lamellae are composed of a very fine central 

 portion, which on account of its gray color, its hardness (4, only slightly higher than that of the groundmass), and its 

 lack of structure, possesses the greatest similarity with the groundmass; only in a few broader places does a faintly 

 indicated granular structure of the central part of the lamellae show itself, but without hatching, which reminds one 

 of the condition of the kamacite in other meteorites. The envelopes of the lamellae are composed of tsenite, which, 

 on account of its bright luster after etching and the faint yellowish color thereby acquired, is easily recognizable. 



The width of the lamellae is very slight, the central part with both envelopes being in the greater number of cases 

 scarcely more than the sixtieth of a millimeter; the length of a lamella is commonly 15 or 20 mm., although it reaches 

 even 30 mm. and over. Where differently arranged lamella? touch one another the one system is for the most part 

 developed entirely undisturbed — its earlier origin identified, whilst the other arises thereon with core and envelope 

 immediately adjacent to the envelope of the first; occasionally, although seldom, they are arranged core to core and 

 envelope to envelope, as proof of the synchronous origin of both systems from the point of common contact. Among 

 the principal framework of the four systems of lamellae, as is customary in the case of skeleton-like structure of crystals, 

 are found irregularly oriented little leaflets, many of them arranged parallel to each other, but some also crosswise; 

 along with these lie very short lamellae, and even small — 1 to 2 mm. long — veinlets in the groundmass, which, grading 

 down to microscopic smallness, occasion the shimmering appearance of the groundmass. 



Besides these principal constituents troilite occurs in roundish, lenticular masses, measuring up to 2 cm. in 

 diameter, which are present in large numbers down to the smallest granules; the larger among them have an envelope 

 of taenite which follows their often somewhat jagged contours, and around this is a second envelope equalizing these 

 unevennesses of gray, structureless iron, similar to the groundmass and yet somewhat different from it, entirely analogous 

 to the condition of such inclusions in many other meteorites; the lamellar system contains no troilite, which was shown 

 by treatment with hydrochloric acid. 



The greatest section surface does not depart so widely (some 13°) from the position of a leucitohedron face; three 

 distinct lamellar systems cross one another at angles of 70°, 61°, and 49° thereon, the fourth is veinlike and broadened. 

 It intersects — as the other section surfaces show — at a very obtuse angle and makes a perpendicular in the triangle 

 formed by the other three, dividing the angle of 61° into two of 44° and 17°, so that the greater angle adjoins that 

 of 49°. The adjoining angles in order are — 



70°, 17°, 44°, 49° (17°+44°=61°) 



Brezina 4 also uses several etchings of this iron to illustrate his method of determining the 

 crystallographic character of a meteoric iron from the Widmannstatten figures, and to prove 

 that the figures in question arise from laminae parallel to the faces of an octahedron. 



Huntington 7 describes the structure as follows : 



The Widmannstatten figures are very fine and not in broad, distinct plates, while some of them are even micro- 

 scopic ; and yet from this iron was obtained a far more perfect octahedron than from any of those with a coarser structure. 

 On etching the faces of such an octahedron it appeared that the majority of the plates, including even the finest micro- 

 scopic markings, followed the direction of the octahedral faces; but certain plates bisect the facial angle of the octa- 

 hedron. These plates, when followed over an edge on to an adjacent face, were seen to be parallel to an octahedral 

 edge, showing that they must be dodecahedral instead of octahedral. 



Thus it appears that the Widmannstatten figures are not solely characteristic of octahedral structure. Further- 

 more, the Butler meteorite seemed to stand between well-marked Widmannstatten figures and the finer lines discovered 

 by Neumann and shown by him to be parallel to cube edges. Some of the Butler figures are coarse enough to be classed 

 unquestionably as Widmannstatten figures; that is, they show the three varieties of iron distinguished by Reichenbach, 

 which he calls the Trias (kamacite, taenite, and plessite); while others of the figures are almost microscopic markings 

 in which distinct plates of kamacite and plessite can not be made out even under the microscope. Between these 

 two extremes there is every gradation. The Butler meteorite has always been classed among the octahedral irons. 



