USEFUL METALS 



Mfl 



of the nickfl consumed in the United States. In fact, practically 

 the entire production is said to be imported into the United 

 States. However a small balance goes to Midland. New 

 Caledonia, as elsewhere noted, is the largest single produ< 

 nickel-bearing minerals in the world (Fig. 121). Nickel also 

 occurs at Revda, southwest of Ekaterinburg, in the Urals nickdif- 

 erous minerals in connection with antigorite serpentine which 

 is associated with metamorphic limestones and mica schists; 

 also at Frankenstein, in Prussian Silesia, in association also 

 with serpentine. 



FIG. 121. Main pit Creighton mine, Sudbury district, Ontario. (After 

 A. E. Barlow, Canadian Geological Survey.) 



The association of the nickeliferous minerals points to one 

 thing of especial interest. Their home is everywhere shown to 

 be connected with the ultrabasic and basic intrusives as perido- 

 tite, norite, diabase and diorite, rather than with the acidic 

 magmas. 



Geological Horizon. The important ore deposits of nickel 

 are in the older geological formations ranging from the pre- 

 Cambrian to the Ordovician. The deposits in Oregon appear 

 to be an exception for they are associated with the post-Creta- 

 ceous, pre-Eocene peridotite. 



