2 Field Columbian Museum — Geology, Vol. III. 



as characterizing Charcas* and referred by him tentatively to 

 minute inclusions of troilite. An examination of the dots in Rodeo 

 with the lens shows them to be minute, shallow, saucer-shaped 

 pits. They are scattered irregularly along the bands of kamacite, 

 and are to be seen in some of the swathing kamacite, but never 

 in the plessite. The tendency of the iron to rust at these points 

 is greater also than at others. They appear therefore, to mark 

 the occurrence of some more soluble ingredient in the kamacite. 

 This is probably not troilite, but may be an iron containing less 

 nickel than the kamacite. The lamellae of the meteorite may be 

 grouped into two classes; one about i mm. in width, swollen, and 

 with wavy outlines, and the other about half as wide, and with more 

 nearly rectilinear outlines. As a rule, these two kinds of lamellae 

 have a different orientation as compared with each other. The 

 kamacite is granular, much lighter in color than the plessite. A con- 

 siderable quantity of swathing kamacite is present. While in general 

 it follows the outline of the inclusions and forms a narrow border to 

 them, at times its outer border is quite independent of the shape of 

 the inclusions and it covers relatively broad areas. The taenite is 

 well developed, silver-white in color, and displays the structure of a 

 section brilliantly on holding one at an angle to the light. The ples- 

 site is not depressed by etching as is the kamacite. At times it occu- 

 pies the meshes alone, while again the meshes may display elaborate 

 combs resulting from skeleton growths of taenite. Scattered irregu- 

 larly through the sections and forming an important feature in the 

 structure of the meteorite, occur numerous inclusions of schreibersite. 

 The form of these inclusions, especially those of large size, is in gen- 

 eral elongated, and rectangular or spindle-shaped. Some of the 

 smaller inclusions, however, are star-shaped, while others have no 

 well-defined form. The largest inclusion noted (shown in the upper 

 right-hand corner of Plate III.) has a length of one and a half inches 

 (4 cm.) and a width of one-fourth of an inch (.5 cm.). The schreiber- 

 site is tin-white in color, brittle, and magnetic, and affords the usual 

 blow-pipe and chemical tests for that mineral. The inclusions are 

 always bordered by a band of swathing kamacite about 1.5 mm. in 

 width. The inclusions, while having no apparent regularity of 

 arrangement among themselves, are usually disposed, especially the 

 elongated ones, parallel to the Widmanstatten figures, or in other 

 words, the octahedral structure of the meteorite. This can well be 

 discerned by a study of Plate III. Another inclusion of an interesting 

 character found in one of the sections was a nodule about one centi- 

 *Wiener Sammlung, 1895, p. 275. 



