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The sedimentary appearance of the thin laminations led to early interpretations that the deposits formed exclusively or mainly by exhalative processes onto the seafloor, hence the term SEDEX. However, recent study of numerous deposits indicates that shallow subsurface replacement is also an important process, in several deposits the predominant ...
Sphalerite is a sulfide mineral with the chemical formula (Zn, Fe)S. [5] It is the most important ore of zinc.Sphalerite is found in a variety of deposit types, but it is primarily in sedimentary exhalative, Mississippi-Valley type, and volcanogenic massive sulfide deposits.
The three main families of sulfide polymetallic ores are identified as volcanogenic massive sulphide family, the sedimentary exhalative family, and the Mississippi Valley type family. The classification of lead-zinc deposits in particular has been varied and resulted in a number of different organizations schemes. [ 1 ]
For example, sedimentary exhalative deposits (SEDEX), are a class of ore deposit formed on the sea floor (sedimentary) by exhalation of brines into seawater (exhalative), causing chemical precipitation of ore minerals when the brine cools, mixes with sea water, and loses its metal carrying capacity.
Sedimentary exhalative (SEDEX) deposits account for 40% of total world zinc production, 60% of lead and a significant proportion of silver. Despite their economic importance however, sedex deposits are relatively rare. A worldwide compilation of sedex deposits indicates that about 70 are known, of which 24 have been or are being mined.
A sulfide deposit is an ore body or rock containing a great deal of sulfide minerals. Articles on this topic include: Seafloor massive sulfide deposits; Sedimentary exhalative deposits; Volcanogenic massive sulfide ore deposit; Massive sulfide deposits
VMS deposits have an ideal form of a conical area of highly altered volcanic or volcanogenic sedimentary rock within the feeder zone, [definition needed] which is called the stringer sulfide or stockwork zone, overlain by a mound of massive exhalites, and flanked by stratiform exhalative sulfides known as the apron.
Molybdenite occurs in high temperature hydrothermal ore deposits. Its associated minerals include pyrite , chalcopyrite , quartz , anhydrite , fluorite , and scheelite . Important deposits include the disseminated porphyry molybdenum deposits at Questa, New Mexico and the Henderson and Climax mines in Colorado .