UNITED STATES MINERAL RESOURCES 



MANGANESE 



By John Van N. Dorr, II, Max D. Crittenden, Jr., and Ronald G. Worl 



CONTENTS 



Page 



Abstract of conclusions 385 



Introduction 385 



Exploitation 386 



Geologic environment 387 



Geochemistry and crustal abundance 387 



Types of manganese deposits 389 



Manganese minerals 389 



Sedimentary deposits 389 



Manganese nodules 390 



Volcanogene deposits 391 



Hypogene deposits 392 



Resources 393 



Identified and hypothetical resources 393 



Reserves 393 



Conditional resources 393 



Hypothetical resources 394 



Speculative resources 394 



Prospecting techniques 396 



Problems for research 396 



General problems 396 



Needs for new prospecting techniques 397 



Technological problems 398 



Selected references 398 



FIGURE 



45. 



Domestic manganese ore production (metallurgi- 

 cal grade), 1943-63, distributed according to 

 sources of output 



TABLES 



75. 

 76. 

 77. 



Production, imports, and consumption of man- 

 ganese ore and concentrates and ferroman- 



ganese, 1966, 1970, and 1971 



Common manganese minerals 



World manganese resources 



Major identified manganese resources of the 

 United States 



386 



386 

 389 

 393 



394 



ABSTRACT OF CONCLUSIONS 



Known minable reserves and known resources of man- 

 ganese are very large in relation to world consumption but 

 are very irregularly distributed throughout the world. The 

 United States has virtually no domestic reserves and its 

 known resources are both very low grade and refractory to 

 economic concentration. The principal hopes of finding do- 

 mestic reserves or resources of conventional types may lie 

 in (1) finding the source of the manganese of the Pierre 

 Shale, conceivably buried under Pleistocene sedimentary 

 rocks in central or western Minnesota or adjacent areas; (2) 

 finding another Molango-type deposit by careful analysis of 

 the distribution of manganese in certain miogeosynclinal 

 carbonate rocks; or (3) finding the source of the high man- 

 ganese concentrations in the Salton Sea brines. Much more 

 promising modes of relieving dependence on foreign sources 

 are by vigorously attempting to perfect techniques of ef- 

 fectively exploiting sea-floor nodules and by dissolving legal 

 impediments to large-scale investment in subsea mining. 

 Maintenance of an adequate national stockpile is essential. 



With respect to world resources, efforts should be made to 

 explore the sedimentary high-grade manganese carbonate 

 bodies, which through weathering have given rise to over- 

 lying rich supergene oxide deposits, in order to establish 

 the tonnage and grade of material that will be available for 

 use when oxide deposits are depleted; the tonnage is prob- 

 ably great. There is some possibility that deposits without 

 the oxidized cap might be found in eugeosynclinal belts in 

 the North American Shield areas. 



INTRODUCTION 



Manganese, a metal rarely seen in elemental form, 

 is essential in two ways to the manufacture of steel : 

 (1) used as a scavenger in molten steel, it combines 

 with sulfur and oxygen, which make steel brittle, and 

 removes them as part of the slag; (2) used as an 

 alloy, it makes steel more resistant to shock or abra- 

 sion. It is used also in the chemical industry and, in 

 dioxide form, as a depolarizer in dry batteries. More 

 than 90 percent of the consumption in the United 

 States is by the steel industry, and no substitute has 

 yet been found despite much effort. About 13-20 

 pounds of manganese is consumed per ton of steel 

 manufactured; therefore the element is essential to 



U.S. GEOL. SURVEY PROF. PAPER 820 



385 



