150 W. T. Schaller — Ludwigiie from Montana. 



Analyses of ludwigite. 

 2 3 4 





FeO.FeoOa 



Ludwigite fi 



•om Hungary 



Ludwigite 





;{MgO.B,03 





analyzed by : 





from 







Ludwig «& 







Ludwig & 



Montana 







Sipocz 



Schaller 



Whitfield 



Sipocz 





FeO . 



. 17-01 



17-67 



15-84 



15-78 



12-46 



7-27 



MgO. 



. 28-61 



26-91 



28-88 



30-57 



31-69 



33-78 



Fe,0, . 



. 37-81 



39-29 



37-67 



35-93 



39-92 



37-37 



Al A • 





















2-27 



BA- 



. 16-57 



15-06 



[17-02J 



12-04 



16-09 



16-94 



MnO. 



. - , - 



tr. 







0-16 



tr. 





H,0- 









0-51 



3-62 







1-13 



H,0 + 











0-82 







1-24 



SiO,.. 











0-36 



. - _ - 







J 



CO,... 











0-90 















100-00 



98-93 100-00 100-10 100-16 100-00 



The second analj'sis (column 6) by Ludwig and Sipocz 

 shows a slight replacement of the ferrous iron by magnesia, 

 carried out to a much larger extent in the mineral from Mon- 

 tana. All new occurrences of ludwigite should be carefully 

 examined chemically, as the possibility of the existence of 

 the ferrous-iron free magnesian borate is strongly indicated by 

 the above analyses. 



Chemical Laboratory, U. S. Geological Survey. 



