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The exploitation of Belgian zinc–lead deposits dates back to prehistoric times. Its apogee was between 1850 and 1870 and the last mine was closed in 1946. During the period 1837–1945, during which time production levels were recorded, the tonnage of exploited metals reached about 1 500 000 tons Pb+Zn with a Zn/Pb ratio of 8–9. The mineralogy of the deposits is generally simple: sphalerite, galena, pyrite or marcasite, and locally Ni- and Co-sulfides. Several ore deposit types may be distinguished, including syndiagenetic-, vein and connected flat-, and paleokarstic types. The syndiagenetic deposits are made up of numerous disseminated-type deposits with low grades and small tonnages. They are linked to reef facies of Frasnian (=Upper Devonian) carbonate rocks. The largest exploited vein-type deposits are hosted in Dinantian (=Lower Carboniferous) carbonate rocks. Lead isotopic studies reveal that the main primary source of the metals is in Middle and Upper Devonian sedimentary rocks. Hydrothermal solutions precipitated their metals at temperatures |
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