UNITED STATES MINERAL RESOURCES 



TELLURIUM 



By D. F. Davidson and H. W. Lakin 



CONTENTS 



Page 



Abstract of conclusions 627 



Introduction 627 



Uses 627 



Crustal abundance 628 



Geochemistry 628 



Resources 629 



References 630 



TABLES 



129. 



Tellurium resources potentially available in 

 identified resources of copper ores, lead ores, 

 coal, and oceanic manganiferous nodules __ 



Tellurium content of annual coal consumption 

 at four operating powerplants in Western 

 United States 



629 



ABSTRACT OF CONCLUSIONS 



The present demand for tellurium is less than the amount 

 available as a byproduct from the copper and lead industries. 

 A shortage of tellurium could develop as a result of a 

 change in the processes of recovery of copper from its ores. 

 In-place leaching of copper from its ores leaves the asso- 

 ciated tellurium undissolved in the waste roclc resulting 

 from the process. Thus, as the use of the leaching process 

 increases at the expense of smelting, the supply of tellurium 

 will decrease. 



Identified resources of copper in the United States are 

 estimated to contain about 13.5 million pounds of recover- 

 able tellurium. Tellurium may be recovered as a byproduct 

 in burning of coal in huge powerplants, paying in part for 

 environmental improvement. The major resource of tellurium 

 is found in manganese oxide nodules on the ocean floors. 



INTRODUCTION 



Tellurium was discovered in a complex group of 

 gold telluride minerals in the ores of Transylvania 

 by F. J. Miiller von Reichenstein in 1782. It is char- 



acteristic of tellurium to form its own minerals in 

 metallic sulfide deposits, although it is very rare. 

 Tellurium is a nonmetallic element; its atomic 

 number is 52 and atomic weight 127.6 ; and it exists 

 in eight stable isotopes. It has a specific gravity of 

 6.24 and melts at 452°C. Tellurium can be obtained 

 in an amorphous or a crystalline form. Amorphous 

 tellurium is brown to black and is produced by re- 

 duction of tellurium solutions. Crystalline tellurium 

 has a trigonal structure, is grayish white, lustrous, 

 and brittle, and is produced by casting the molten 

 element. In a thin film, tellurium is dull purple; its 

 vapor is orange yellow. 



USES 



Tellurium is marketed as a steel-gray powder, 

 and in slabs, tablets, and sticks. The usual commer- 

 cial grade is about 99.7 percent tellurium with 

 selenium and copper as the principal impurities. 

 Grades of 99.99-|- and 99.999+ percent tellurium 

 are available. About 18 percent of the tellurium pro- 

 duced is sold as copper tellurium alloys (40-50 per- 

 cent tellurium) and ferrotellurium (50-58 percent 

 tellurium) (Lausche, 1967). 



About 80 percent of the 221,000 pounds of tellu- 

 rium used in the United States in 1968 went into 

 the primary metal industries. Low-carbon steels 

 containing 0.02-0.2 percent tellurium have better 

 machinability. Tellurium is also used in iron or 

 steel to reduce the adsorption of nitrogen, to act 

 as a weak deoxidizer, and to minimize pinhole por- 

 osity. Less than 1 percent tellurium in copper im- 

 proves machining properties of the copper without 

 effecting the electrical conductivity or hot working 

 properties of the metal. Lead containing 0.05 per- 

 cent of tellurium has added resistance to corrosion. 



The rubber industry accounted for about 10 per- 

 cent of the tellurium used in the United States in 

 1968. Tellurium is used both as the element and as 

 tellurium diethyldithiocarbamate in synthetic and 



U.S. GEOL. SURVEY PROF. PAPER 820 



627 



