442 /less and Wells — Occurrence of Struverite. 



Ilmen Black 



TiO, 



Cb 



Craveggia. 

 I 



41-20 



23-48 ' 



Mts. 

 II 

 53-04 

 21-73 

 14-70 



10-56 



trace 



Hills. 

 Ill 

 49-1 

 6-4 



Ta 



23-48 



35-7 



SnO, 



FeO 



11-38 



1-3 



7-5 



MnO 



CaO 



MgO 



trace 



-51 



0-17 





Sp.gr... 



100-22 

 5-59 



100-03 

 5-14 



100-00 

 5-25 



Summary. 



The occurrence and analysis of a mineral containing titanium, 

 tantalum, iron, columbium and tin is described. Crystallo- 

 graphically it belongs to the rutile group. Chemically it is 

 essentially titanium oxide with iron tantalate and columbate, 

 the tantalate being in excess of the columbate. Tin is an un- 

 essential minor constituent. Its formula approximates to 

 Fe(Ta,Cb)„0. 6 6TiOv It is considered to belong to a group 

 of minerals whose members Prior and Zambonini designated 

 struverite. 



