704 



UNITED STATES MINERAL RESOURCES 



Brunswick, and the Buchans mine in Newfound- 

 land. Other stratabound massive sulfide deposits in 

 metamorphic rocks have been mined in western 

 Europe, as well as in various parts of Russia. Rela- 

 tive newcomers belonging to this very important 

 class of zinc-bearing deposits include those at 

 Prieska in South Africa and in Ontario and Que- 

 bec — for example, Kidd Creek, Mattabi, and Ruttan 

 Lake. (See McLeod, 1965; Douglas, 1970; and South 

 African Mining and Eng. Jour., 1972.) 



Classified with the stratabound massive sulfides 

 are that well-known Kuroko ores of Japan. Although 

 these deposits are altered very slightly, if at all, 

 they have most of the characteristics ascribed to 

 this class of deposit. The Kuroko deposits range 

 widely in size; some contain more than a million 

 tons of zinc in ore consisting of fine-grained mixtures 

 of sphalerite, galena, chalcopyrite, and iron sulfides. 



Massive sulfide and other stratabound deposits in 

 metamorphic rocks that have produced significant 

 quantities of zinc in the United States are those in 

 the Ducktown district of Tennessee, in the Jerome 

 district of Arizona, in the Balmat-Edwards district 

 of New York, and in the Franklin Furnace-Sterling 

 Hill district of New Jersey. The latter two localities 

 in New York and New Jersey differ from the others 

 by being closely associated with Precambrian mar- 

 ble. The New Jersey deposits are almost unique 

 among the major zinc deposits of the world in that 

 the ore minerals are predominantly franklinite, 

 willemite, and zincite rather than the more com- 

 mon, apparently ubiquitous, sphalerite. The New 

 York and New Jersey districts together have pro- 

 duced more than 5 million tons of zinc and have re- 

 sources of at least that much more. 



STRATABOUND DEPOSITS IN CARBONATE ROCKS 

 (MISSISSIPPI VALLEY- AND ALPINE-TYPE DEPOSITS) 



Another major type of zinc-lead deposit is found 

 in platform carbonate rocks in many parts of the 

 world. In some, the ore minerals occur as open- 

 space fillings in breccias; in others, the minerals 

 formed chiefly by replacement. The ores in many 

 districts are relatively low grade and occur as 

 extensive bodies within broadly mineralized regions 

 covering hundreds of square miles. They are classi- 

 fied as stratabound because they are confined to 

 relatively thin zones, which are generally not more 

 than several hundred feet thick, in much thicker 

 carbonate sequences. Many districts are, for the 

 most part, relatively undisturbed tectonically, as in 

 the Mississippi Valley of the United States or in the 

 Upper Silesian province of Poland. Elsewhere, as in 

 the Appalachian and Alpine regions of North 



America and Europe, platform carbonates with their 

 zinc deposits already in place have been deformed 

 structurally by later tectonism. Although most of 

 these deposits produce both zinc and lead, zinc is 

 generally dominant. A major exception is the lead 

 district of southeastern Missouri where the deposits 

 contain about 5 percent lead, generally less than 1 

 percent zinc, and minor quantities of copper, silver, 

 cadmium, cobalt, nickel, and germanium. This dis- 

 trict contains one of the largest known concentra- 

 tions of lead in the world. On the other hand, most 

 of the deposits in some districts, for example, the 

 major producing deposits of the East Tennessee 

 districts and those of Middle Tennessee now being 

 explored and developed, have only sphalerite and 

 contain little more than trace amounts of galena. 

 Other districts in the United States containing 

 stratabound deposits in carbonate rocks are the 

 Upper Mississippi Valley district of the Wisconsin- 

 Illinois region, the famed Tri-State district in Kan- 

 sas, Missouri, and Oklahoma, and the Friedensville 

 district in eastern Pennsylvania. The major deposits 

 in the Metaline district in northeastern Washington 

 are also considered to be of this type, although they 

 appear to be much more structurally disturbed and 

 metamorphosed than the previously mentioned de- 

 posits. Elsewhere, examples of significant deposits 

 of this type are at Pine Point in western Canada; 

 in several countries in northwestern Africa; in the 

 European Alps from France eastward through Italy, 

 Austria, and Yugoslavia; and in the Upper Silesian 

 district of Poland. The Broken Hill district in Zam- 

 bia, the Balmat-Edwards district in New York, and 

 the Franklin Furnace- Sterling Hill districts in New 

 Jersey are considered by some investigators to be 

 highly altered or metamorphosed equivalents of this 

 class. (See various authors in Ridge, 1968; also in 

 Brown, 1967, and in Wedow and others, 1971.) 



STRATIFORM DEPOSITS 



The stratiform deposits containing zinc have also 

 been referred to as stratabound deposits of synge- 

 netic or diagenetic origin or simply as sedimentary 

 deposits. Stratiform deposits should not be confused 

 with stratabound deposits. Stratiform indicates the 

 deposit is in the form of a stratum interbedded 

 with other strata, for example, the Clinton-type 

 sedimentary iron ores, whereas stratabound deposits 

 may be crosscutting but are confined to a zone 

 bounded by strata. In a general sense, all stratiform 

 deposits are stratabound, but not all stratabound 

 deposits are stratiform. (Note: Usage of the terms 

 stratabound and stratiform in this chapter is some- 

 what different from usage in some chapters. — Eds.) 



