NO. 20 HELT TOWNSHIP METEORITE PERRY 3 



one general direction, with a few short ones at right angles and occa- 

 sional rounded areas. Most of the bands have an oriented sheen, 

 though not strongly marked ; some show little or no variation as the 

 direction of the light changes. 



The meteorite consists almost entirely of kamacite, with few plessite 

 fields, a sparing development of taenite, and numerous schreibersite 

 inclusions. Generally, the kamacite bands are not separated by taenite 

 lamellae, but only by invisible boundary lines along which contrasts of 

 structure appear on etching. Often small bodies of schreibersite or of 

 taenite, elongated and of various shapes, appear along such boundaries, 

 but such inclusions are rarely continuous for more than short 

 distances. 



Near one corner of the polished surface is an area about 2 cm. 

 square which shows no definite figures. In this area the taenite is in 

 short thin lines, or occasional baguettes or irregular shapes, with one 

 sprangling inclusion about 2 by 5 mm. in size. 



Plessite fields are few, consisting mostly of eutectiform areas of 

 taenite lamellae of the type shown in plate 2, figure I, termed "per- 

 litoid" by some of the German writers. Other areas are filled with 

 coarse oriented skeletal growths (pi. 2, fig. 2; pi. 3). No fields filled 

 with fine taenite particles or threads, nor areas of dark (micro) 

 plessite, were observed. 



Plate 5 shows a taenite lamella with breaks suggesting the appear- 

 ance of faulted rock strata, a result of local deformation. Similar 

 but less conspicuous displacements are observable in other spots (pi. 8, 

 fig. 1). Such displacements always coincide with Neumann lines, 

 and in the area shown in plate 5 a considerable movement took place 

 along the gliding planes marked by some of the lines. 



Neumann lines are caused by shock or quick stress, and it has been 

 suggested by various writers that they may have been produced when 

 a mass of meteoric iron struck the earth. In the present case it is 

 clear that the disturbance that produced the displacements (and 

 simultaneously the Neumann lines) must have occurred before the 

 mass reached the earth, and prior to the partial alteration of structure 

 produced by reheating during flight, which in places obliterated the 

 Neumann lines. The shock of the impact of such a small mass upon 

 soft earth would be comparatively slight ; but the violent stresses 

 resulting from atmospheric pressure during flight (sufficient often to 

 cause cracks in iron meteorites, and sometimes disruption) would 

 readily account for evidences of deformation, ranging all the way 

 from light Neumann lines to pronounced displacements of structure. 



