440 



UNITED STATES MINERAL RESOURCES 



been proposed, and are summarized by Cornwall 

 (1966). 



Other nickel-bearing sulfide deposits occur along 

 faults or shear zones; these are clearly epigenetic 

 and the place of deposition was structurally con- 

 trolled. 



NICKELIFEROUS LATERITE DEPOSITS 



Laterite has formed over large areas during long 

 periods of intensive weathering and erosion, mainly 

 in tropical to subtropical climates, where stable 

 landmasses have gradually been reduced to almost 

 flat featureless peneplains. Such a period of erosion 

 took place during Tertiary time in many parts of 

 the world. Where the rock exposed at the surface 

 was peridotite (composed essentially of olivine and 

 pyroxene), dunite (all olivine), pyroxenite (all 

 pyroxene) , or serpentinite (serpentinized perido- 

 tite), and laterite that was developed is almost in- 

 variably rich in iron and nickel. 



The laterite formed from the weathering of ser- 

 pentinite is richest in iron, generally containing 

 45-55 percent. The nickel content of this laterite 

 commonly averages about 1 percent, ranging from 

 about 0.9 to 1.3 percent for large volumes of mate- 

 rial. These deposits are called nickeliferous iron lat- 

 erite. The mode of occurrence of the nickel in this 

 laterite is not known; most likely the nickel is in- 

 cluded in the goethite, limonite, and serpentine 

 minerals, which are the major constituents. Huge 

 deposits of nickeliferous iron laterite, similar to 

 those in Cuba, the Philippines, and Indonesia, are 

 not known in North America, but several smaller 

 deposits have been thoroughly explored in Califor- 

 nia, Oregon, and Washington. 



The other type of nickeliferous laterite is known 

 as the nickel-silicate type, because a significant 

 part of the nickel occurs either as the hydrosilicate 

 garnierite or as nickel-bearing talc or antigorite. 

 This laterite has formed from the weathering of 

 fresh peridotite, dunite, and, to a lesser degree, 

 pyroxenite. The iron content is less than 30 percent 

 in most laterite of this type; the SiOa content, 

 which is very low in the iron laterite, may be as 

 much as 30 percent; and the nickel content exceeds 

 1.5 percent and averages about 1.6 percent for large 

 tonnages. The largest known deposits of nickel- 

 silicate laterite occur in New Caledonia and Indo- 

 nesia. A moderately large deposit occurs in the 

 United States at Riddle, Oreg. 



RESOURCES 



IDENTIFIED RESOURCES 



This discussion considers first the world sulfide 



resources and second the world laterite resources 

 of nickel. The basic figures are given in tables 87 

 and 88 and are considered conservative. The United 

 States resources are given by States; resources of 

 other nations are listed by country. 



The United States sulfide resources are quite large 

 (6.9 billion tons) but low grade (0.21 percent Ni). 

 The very large estimate of nickel in the Duluth 

 Gabbro near Ely, Minn., is based on data recently 

 released by the Minnesota Geological Survey (P. K. 

 Sims, written commun., 1972). Canadian reserves 

 of minable ore are the world's largest with probably 

 close to 2 billion tons of material that can be mined 

 under present economic conditions. Australia prob- 

 ably has great potential for increasing the present 

 estimate of 400 million tons and the yearly produc- 

 tion rate is growing rapidly. South Africa also has 

 potential for greater than the 200 million tons esti- 

 mated here. U.S.S.R. tonnage is probably greater 

 than 100 million, but grade is probably less than 

 0.6 percent nickel. 



Table 87. — World nickel-sulfi.de identified resources 



[Identified resources are specific, i<3entified mineral deposits that may or 

 may not be evaluated as to extent and grade, and whose contained 

 minerals may or may not be profitably recoverable with existing tech- 

 nology and economic conditions] 



Ni 

 Area Tons of ore (percent) 



United States: 



California 100,000 1.5 



Colorado 70,000 .8 



Montana (Stillwater)' 150,000,000 .25 



Missouri 10,000,000 .5 



Nevada 30,000 .3 



Pennsylvania (Gap) 800,000 .7 



Washington 100,000 .9 



Minnesota (Ely)= 6,500,000,000 .21 



Alaska, Brady Glacier 200,000,000 .25 



Yakobi Island 20,000,000 .3 



Funter Bay 600,000 .35 



Maine 10,000,000 1 



Total (0.21 percent 



Ni avg) 6,900,000,000 



Canada: 



Thompson district: 



Thompson mine 150,000,000 3.0 



Mystery Lake deposit 200,000,000 .45 



Moak Lake deposit 400,000,000 .7 



Others 250,000,000 1 



Total (1.0 percent 



Ni avg) 1,000,000,000 



Sudbury district 400,000,000 1.5 



Other Canadian 100,000,000 1.5 



Other Canadian 200,000,000 .2 



South Africa 200,000,000 1 



Norvi^ay 2,000,000 1 



Burma 25,000,000 .3 



Australia 300,000,000 .6 



Australia 100,000,000 1.5 



U.S.S.R. 100,000,000 .6 



1 Also contains 0.25 percent Cu. 

 ^ Also contains 0.64 percent Cu. 



