12 PEOCEEDIISrGS OF THE NATIONAL, MUSEUM vol. 72 



These figures are less satisfactory for mineralogical interpretation 

 as there was unquestionably some metallic iron in the material 

 analyzed, increasing the ferrous iron content by its amount as well 

 as by the hydrogen generated by its solution in acid. The results 

 interpreted in combination are, however: 



Per cent 



Magnetite (FeO.Fe^Oa) 30.68 



Trevorite (NiO.FeoOs) 21.09 



FeaOs 30. 50 



H2O ■ ^__ 12.44 



Insol 1. 86 



96.57 



Since there is much too little remaining FeaOg to form the com- 

 pound 2Fe203.3H20 with all of the water, these constituents are 

 stated separately above. Calculation shows the FegO,: water ratio 

 to be 1 : 3.82. There can thus be represented in this meteorite scale 

 no anhydrous FegOg either magnetic or nonmagnetic. The magnetic 

 content indicated above, even were it corrected for the effect of metal 

 in the powder, is much higher than in the two preceding examples, a 

 condition which may depend to a considerable degree to the peculiar- 

 ities of weathering under the climate of Greenland as compared with 

 the climates of Arizona and Kansas. The magnetite and the trevorite, 

 together amounting to over 50 per cent are ample to explain the mag- 

 netic properties of the material. 



FERROMAGNETIC POLARIZED ANHYDROUS IRON OCHER FROM 



OKLAHOMA 



In a lot of materials received for examination from Mr. O. C. 

 Duncan of Durant, Okla., was a specimen of impure oxide of iron 

 which proved to be of unusual interest. The sample was accompanied 

 by a number of other materials, chiefly bentonitic clays, and was 

 said to have come from near Durant, but no additional information 

 regarding the occurrence has been received. 



At first observation the material has the appearance of an ordinary 

 compact red-brown ocher. Its color, both in mass and finely ground, 

 is cinnamon rufous (ll'^) Ridgway and the mineral is entirely dull 

 and lusterless. It forms small rounded masses up to 1 centimeter 

 across which are frangible enough to be broken with the fingers and 

 are easily crushed in an agate mortar by only moderate pressure of 

 the pestle. Ordinarily this would have been reported as a common 

 ocher but it was observed that the grains had a strong tendency to 

 cohere and the finer powder attached itself to larger grains in mossy 

 aggregates after the manner of lodestone. The material was not 

 only highly ferromagnetic but it was also strongly polarized. Micro- 



