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 lamella of the meteorite may be 
grouped into two classes; one about 1 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 lamelle 
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 tenite 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 tenite. 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 II]. Another inclusion of an interesting 
character found in one of the sections was a nodule about one centi- 
*Wiener Sammlung, 1895, p. 275. 
