ZINC 



707 



sissippi Valley-type deposits). T. H. Kiilsgaard and 

 B. A. LaHeist (written commun., 1962) showed in 

 their estimate of resources that these two types of 

 deposits each contain about one-third of the total. 

 Furthermore, their estimate indicates that replace- 

 ment, vein, and contact-metamorphic deposits, in 

 that order, dominate the remaining third of the 

 recoverable resources. They did not list separately 

 the deposits herein designated as stratiform and as 

 formed by supergene enrichment or laterization. 

 Bachau (1971, p. 8-10) estimated that the massive 

 sulfide ores and the Mississippi Valley-type deposits 

 contain more than two-thirds of the total of exploit- 

 able zinc. Announcements in recent mining maga- 

 zines show that most of the major new discoveries 

 belong to these two major types of deposits, and 

 much of the undiscovered recoverable zinc resources 

 is in these categories. However, other announce- 

 ments give credence to the belief that oxidized 

 deposits formed by laterization may be a category 

 to exploit. This type of deposit holds the promise of 

 large, shallow, high-grade, nonsulfide ores, examples 

 of which are the deposits at Vazante in Brazil, in 

 the Pa Daeng Mountains of Thailand, and in the 

 Beltana district of South Australia. All these de- 

 posits are under development, if not in actual pro- 

 duction. 



Recoverable identified resources of the United 

 States are listed by major geologic regions in table 

 154, and those of the world are given by continent 

 in table 155. 



Table 154. — Recoverable identified zinc resources of the 

 United States grouped by major geologic regions 



Zinc content 

 Region (millions of metric tons) 



Appalachian^ 16.4 



Mississippi Valley" 19.2 



Rocky Mountain^ 7.3 



Pacific Coast* 2.1 



• Chiefly the Franklin-Sterling Hill, Friedendsville, and Edwards-Balmat 

 districts in New Joi-sey, Pennsylvania, and New York, as well as the 

 Austinville-Ivanhoe district in Virginia and the several East Tennessee 

 districts. 



= Chiefly the Tri-State and Upper Mississippi Valley districts and the 

 Missouri lead belts: also includes large inferred (possible) recoverable 

 resources in the newly deve'oping Middle Tennessee districts. 



=^ Major sources include the Butte district in Montana: the Gilman, Lead- 

 ville, and several smaller districts in Colorado: the Eureka. Pioche, and 

 White Pine districts in Nevada: the Bingham, Park City, and Tintic dis- 

 tricts in Utah: the Central, Pecos, and Mogo'lon districts in New Mexico; 

 and the Big Bug, Bisbce, and Verde districts in Arizona. 



■' Chiefly the Metaline and Northport districts in Washington and the 

 Coeur d'Alene district in Idaho; includes small districts in California, 

 Oregon, and Alaska. 



The total of identified subeconomic (conditional) 

 resources and both recoverable and subeconomic 

 undiscovered resources is given as 4,850 million 

 metric tons of contained zinc (table 153). Tonnage 

 of selected examples of the types of zinc occurrences 

 that contribute to this total are presented in table 

 156. 



Table 155. — Recoverable identified zinc resources of the 

 world 



84 

 16 

 58 

 14 

 42 

 21 



Continent 



North America 

 South America . 



Europe 



Africa 



Asia 



Australia 



Total 



Table 156. — Selected examples of types of zinc occurrences 

 that contribute to the total of conditional ' and undiscov- 

 ered zinc resources of the ivorld 



Zinc content 

 Example (millions of 



metric tons) 



Kupferschiefer of Europe 1,000 



Deep-sea manganese nodules 750 



Metal-bearing Red Sea muds 3 



Deep-lying zinc deposits in Washington State — 24 

 Zinc-bearing pyrite at United Verde mine, 



Arizona 1 



Deposits in platform carbonate rocks : 



1) Mississippi Valley-type deposits 600 



2) Zinc in dolomitic evaporites and related 



deposits '^00 



Paleoequivalents of Red Sea muds 60 



High-grade lateritic ores 30 



Zinc byproduct from manufacture of fertilizer 



from selected phosphorites 5 



Zinc coproduct or byproduct from massive 



sulfide or kuroko type deposits 300 



1 CONDITIONAL RESOURCES: Specific, identified mineral deposits 

 whose contained minerals are not profitably recoverable with exist- 

 ing technology and economic conditions. 



Among the known lower grade or subeconomic 

 zinc resources are the extensive deposits of the 

 Kupferschiefer and related beds in the Permian 

 Zechstein Formation of Europe (Dunham, 1964). 

 Resources in these beds must exceed 1 billion tons 

 of zinc ; in one area alone in East Germany, Richter- 

 Bernburg (1941) estimated the contained zinc at 

 200-250 million tons, and comparable though lesser 

 quantities of lead and copper accompany the zinc. 

 An example of the type of deposit that remains as 

 a resource until beneficiation or other extractive 

 techniques are improved is the zinc-bearing pyrite 

 at the United Verde mine in Arizona, where about 

 three-fourth million tons of zinc occurs in 12 million 

 tons of pyritic ore (Anderson and Creasey, 1958). 

 Other subeconomic types of deposits with significant 

 zinc resources are mineralized bodies of relatively 

 low tenor but of the same type as those currently 

 being mined from carbonate rocks in the Mississippi 

 Valley and Appalachian regions of the United States 

 and elsewhere in North America. The resource po- 

 tential for this type of deposit in North America 

 must exceed several hundred million tons of zinc, 

 particularly if that for the East Tennessee and the 

 newly discovered Middle Tennessee districts is esti- 



