AKT. 21 OXIDATION OF METEORIC IRONS SHANNON 15 



unattracted. No color difference could be detected between the 

 attracted and the unattracted portions. 



The attracted portion was analyzed partially with the following 



results : 



Martite ore, Durango 



Insoluble 10. 84 



FeiOa 80. 72 



FeO —J 2. 58 



ao 1. 36 



Undetermined 4. 50 



100. 00 

 These figures, combined as previously, gave : 



Quartz, etc 10. 84 



Magnetite 8. 31 



Limoriite 9. 42 



Hematite 66. 93 



Undetermined 4. 50 



100. 00 

 The amount of magnetite indicated in this table is just about what 

 can be observed in polished surfaces under the reflecting microscope 

 so that this constituent is present in mechanical admixture and not 

 in solid solution. This is not enough to explain the magnetic attrac- 

 tion exhibited by the whole material and it seems certain that a con- 

 siderable portion of the ferric oxide above tabulated as hematite 

 must be the ferromagnetic form. The martites have been carefully 

 studied by Sosman and Hostetter ^^ who found a number of martites 

 which consisted of granular or fibrous aggregates of homogeneous 

 material apparently contained ferrous iron in solid solution. 



'*R. B. Sosman and J. C. Hostetter. The ferrous iron content and magnetic suscepti- 

 bility of some artificial and natural oxides of iron. Bull. Amer. Inst. Min. Eng., No. 126, 

 June, 1927. 



o 



