THE STRUCTURE OF METEORITES 59 



to a dodecahedral face there will be two systems of bands inter- 

 secting at angles of 109 28' and two others parallel to each 

 other which will bisect this angle (Fig. 4). Sections in any 

 other direction (obviously by far the most common) will pro- 

 duce bands running in four directions and intersecting at unequal 

 angles (Fig. 5) . A small number of iron meteorites show a cubic 

 rather than an octahedral crystallization, i. e., they are formed of 

 plates arranged parallel to the faces of a cube. These are known 

 as " cubic irons," or hexahedrites. A still smaller number exhibit 

 no crystalline structure nor Widmanstatten figures. These are 

 known as amorphous irons or ataxites. The relative numbers of 

 these kinds of irons given in Brezina's classification are, of the 

 octahedral irons, 125; of the cubic irons, 26; and of the atax- 

 ites, 14. Among the octahedral irons the particular figures 

 exhibited will vary slightly with almost every fall, on account 

 of varying width, length, shape and arrangement of the bands 

 and abundance and forms of included matter. Width of bands 

 is made by Brezina the basis of classification of the octahedral 

 irons. He describes the widths as varying from more than 

 2.5 mm to less than 0.1 mm . When the intimate structure of the 

 bands themselves is considered, they will be found to consist 

 of a broad band of dull luster and iron gray color depressed 

 below the surface when etched or covered with a thick layer of 

 oxide when heated, bounded on either side by thin lamellae of 

 bright luster and silver white to yellow color, which stand out 

 in relief or are little oxidized. To the broadly banded alloy, 

 Reichenbach, who first investigated this structure, gave the 

 name of Balkeneisen or kamacite, from icafxa^, a pole or shaft. 

 To the narrow banded alloy he gave the name of Bandeisen or 

 taenite, from raivia, a fillet or ribbon. When angular interstices 

 occur between the intersecting bands they are often filled 

 with an alloy intermediate in properties between kamacite and 

 taenite. To this Reichenbach gave the name of Fulleisen 

 or plessite. The three alloys together he called " the triad." 

 Chemical analysis of the members of the triad shows them to be 

 alloys of nickel and iron, the first two of which have a fairly 



