2 PROCEEDINGS OF THE NATIONAL MUSEUM vol.72 



the statement by Merrill ^ that, in the oxidation of the Admire pallasite 

 " 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." While this was an 

 original observation of some importance. Doctor Merrill overgener- 

 ously credited priority to J. Lawrence Smith, while the paper by 

 Smith cited deals not with the natural products of oxidation but with 

 the properties of the oxide prepared from the metal of meteoric irons 

 in the laboratory. The attention of the present writer has from time 

 to time been directed to the subject of the oxidation products of mete- 

 orites through work under Doctor Merrill's direction and received 

 impetus through examination of the Coldwater, Kans., material 

 described below and considered by him to be in all probability a 

 completely oxidized meteoric iron. This shortly preceded the ap- 

 pearance of a paper by Sosman and Posnjak^ on "ferromagnetic 

 ferric oxide, artificial and natural." Almost simultaneously with the 

 appearance of the latter paper there was received at the United States 

 National Museum a very striking example of magnetic ferric oxide, 

 the polarized iron ocher from Durant, Okla., as described in detail 

 below. In previous descriptions of oxidized meteorites it has been 

 assumed that the iron oxidized first to magnetite which gradually 

 went over to limonite on further oxidation and hydration despite the 

 very low content of ferrous oxide shown by analysis. In describing 

 the " shale balls " of the Canon Diablo locality Farrington assumed 

 to account for this the presence of magnetites into which the nickel, 

 cobalt, and copper occupied the place of the bivalent iron of ordinary 

 magnetite. The emphasis placed by Sosman and Posnjak on the fact 

 that magnetite might readily oxidize to an anhydrous ferric oxide 

 retaining the magnetic properties of the magnetite suggested the pro- 

 priety of a further investigation into the nature of the material 

 formed from meteoric iron. There are accordingly considered in 

 detail below the Canon Diablo shale balls; the Coldwater oxidized 

 iron and the scale from the York, Greenland, iron. In comparison 

 there are described the Durant, Okla., ocher and a martite iron 

 ore typical of the great deposits of Durango, Mexico. 



PURPOSE OF THE INVESTIGATION 



The problems presented for solution were briefly : 

 First. Does meteoric iron oxidize to fine-grained magnetite as the 

 first product of atmospheric weathering? 



g "^ George P. Mein-ill. A newly found meteorite from Admire, Lyon County, Kans. 

 Proc. U. S. Nat. Mus., vol. 24, p. 910, 1902. 



"R. B., Sosman and Eugene Posnjak. Journ. Wash. Acad. Sci., vol. 15, pp. 329-342, 

 August, 1925. 



