UNITED STATES MINERAL RESOURCES 



PLATINUM-GROUP METALS 



By Norman J Page, Allen L. Clark, George A. Desborough 

 and Raymond L. Parker 



CONTENTS 



Page 



Abstract of conclusions 537 



Introduction 537 



Exploitation 537 



Geologic environment 538 



Geochemistry 538 



Major minerals of the platinum elements 538 



Classification of deposits 538 



Stratiform complexes 539 



Concentric complexes 540 



Alpine complexes 540 



Other mafic-rock environments 540 



Placers 540 



Minor occurrences 540 



Resources 541 



Identified and hypothetical resources 541 



Speculative resources 542 



Prospecting techniques 543 



Problems for research 544 



References cited 544 



TABLES 



110. 



111. 



112. 



113. 



114. 



Page 



Principal minerals and domestic occurrences — 539 

 Composition, in weight percent, of ferroplati- 

 num 540 



Identified, hypothetical, and speculative re- 

 sources 541 



Concentrations of platinum, palladium, rho- 

 dium, and iridium, southeastern Alaska 542 



Correlations of maximum platinum-palladium 



concentrations, southeastern Alaska 543 



ABSTRACT OF CONCLUSIONS 



The United States produces only 1-2 percent of the plat- 

 num metals that it uses and is therefore virtually totally 

 dependent upon foreign supplies; accordingly, the hypo- 

 thetical and speculative resources in Alaska, Montana, Cali- 

 fornia, Oregon, and Washington are of some interest for 



possible future platinum production. More precise evalua- 

 tion of these resources will not be possible without improved 

 analytical techniques for the platinum-group metals at con- 

 centrations less than 10 parts per million. The current lack 

 of such techniques greatly hinders geological, geochemical, 

 petrological, and mineralogical research necessary to evalu- 

 ate the potential platinum resources. 



INTRODUCTION 



Platinum, palladium, iridium, osmium, rhodium, 

 and ruthenium are the platinum-group metals. Plati- 

 num and palladium are the most abundant of this 

 group, but all these metals are essential to modern 

 industry where their applications are based on their 

 catalytic properties, electrical conductivity, and re- 

 sistance to chemical corrosion, heat, and oxidation. 

 About 1.3 million ounces per year of platinum-group 

 metals (Ageton and Ryan, 1970) are consumed in 

 the United States (1) by electrical manufacturers as 

 electrical contacts in high-precision instruments and 

 insoluble anodes for metallurgical processing; (2) 

 by the chemical industry as catalytic gauze for oxi- 

 dation of ammonia and the manufacture of nitric 

 acid; (3) in petroleum refining as a catalyst to pro- 

 duce high-octane gasoline ; (4) in dental and medical 

 devices; (5) in decorative arts and jewelry; and (6) 

 as spinnerettes used in manufacturing glass and syn- 

 thetic fibers. 



The United States produces only 1-2 percent of the 

 platinum metals that it uses and is therefore almost 

 totally dependent upon foreign suppHes. The major 

 sources are the Republic of South Africa, U.S.S.R., 

 Canada, and Colombia. 



EXPLOITATION 



Platinum metals have a long and somewhat erratic 

 history of exploitation beginning in the 7th Century 

 B.C. when a single forged grain of platinum was used 

 as a hieroglyphic character by an Egyptian artisan 

 to decorate an etui. It was reported to have been used 



U.S. GEOL. SURVEY PROF. PAPER 820 



537 



