910 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxiv. 
maiistattian figures, but there is brought out a prominent line of 
demarcation between the outer zone of iron and the inner, very 
brilliant thin plate which, though suggestive of ta^nite, proves to be 
schreibersite, as already noted/ So far as I have been able to deter- 
mine, but one nickel-iron alloy exists, that corresponding most nearly 
to kamacite, as noted below. 
The general structure of the meteorite, as revealed bv the micro- 
scope in thin sections, is shown on Plate LIV. Weathering, as already 
noted, has produced extensive alteration in the metallic portions of 
the rock. Naturally, the lawrencite has been the first to yield, and 
following this, the troilite and native iron, the schreibersite being 
left standing in relief and quite conspicuous. 
The first product of the oxidation of the iron is not limonite, but a 
highly lustrous — on polished surfaces, blue — material which crushes 
down readily to a fine brown magnetic powder." On further exposure 
this goes over into ordinarj' limonite. Where the oxidation has gone 
on largel}^, the silicates are shattered, and veins of the oxidized 
material traverse them in every direction, producing a network of fine 
lines which, in the thin sections, show up with a pronounced blue 
reflection, at first scarcely distinguishable from the native iron itself. 
A chemical analj^sis of the meteorite as a whole has not been 
attempted, as it was felt such would be of little value, owing to its 
extremely coarse nature and the varying proportions of metallic and 
silicate constituents. Carefulh' separated bits of the olivine, free 
from inclosures or oxidation products, jdelded the following results: 
Per cent. 
SiOo 39. 1-i 
MgO 47. 63 
FeO - 13. 185 
Total 99. 955 
This olivine, in the thin section, it may be well to note, showed at 
times a well-defined and quite regular pinacoidal cleavage, which, on 
basal sections, so closely resembled the prismatic cleavage of enstatite, 
that the true nature of the mineral was ascertained only by noting the 
position of the plane of the optic axes. 
The analyses given below were made for me by Mr. Wirt Tassin, 
assistant curator in the Division of Mineralogy. A portion of the 
mass relatively rich in iron was taken. This was carefullv cleansed 
mechanically from any visible traces of silicates or oxidation pro- 
ducts, the cleansed material amounting to 3.3209 grams. Of this 0.07 
1 The investigations on this meteorite and on that of Casas Grandes, studied by Mr. 
Tassin, lead us to feel that schreibersite occurs more frequently in thin plates, 
simulating tpenite, than is commonly supposed. 
- This agrees with observations made by J. Lawrence Smith in 1875 on other irons. 
See Original Researches, pj:). 480-486. 
