854 H. L. PRESTON 



iferous iron in its center. The slices show fractures more or less 

 extending across their surfaces along the natural cleavage faces 

 which are the edges of the kamacite plates, and in some 

 instances the rhombic form produced by the Widmanstatten 

 figures, as is the case in the San Angelo meteorite, 1 are strongly 

 outlined by these fissures. 



Upon etching the iron the Widmanstatten figures are readily 

 brought out by acids. These are particularly sharp and clear, 



Fig. 2. — Showing pyramidal torm. (Two-fifths actual size.) 



and of large size, as shown in Fig. 3. The kamacite plates 

 average from 1 to 1.5 mm in diameter, with an occasional one 

 of 2 mra . They are unusual in the fact that they extend in an 

 unbroken line in many instances from 90 to 120 mm in length. 

 The taenite occurs in minute films between the kamacite plates. 



The plessite patches are comparatively small for an iron of 

 such coarse crystallization. Some of these patches show no 

 structure when etched, except a slightly pitted surface, while 

 others are prominently made up of alternate layers of kamacite 

 and taenite, producing sharply the so-called Laphamite lines. 



Schreibersite is not visible on the etched surfaces microscopi- 

 cally, not even surrounding the troilite nodules, as is usually the 

 case. 



1 American Journal of Science, Ser. 3, Vol. V, pp. 269-72. 



