Sphalerite trace constituents

Just as trace constituents of mineral deposits can act as conventional geochemical pathfinders, trace volatile constituents are potentially gaseous pathfinders. Some sulphide minerals, in particular sphalerite, accommodate trace quantities of Hg. When hberated into... 

In contrast to the extensive data collected on trace-mineralized rocks between ore districts, less information is available on the arsenic contents of the ore deposits. Because iron sulfide minerals are typically gangue phases, they are commonly ignored in trace element studies of ore deposits, which tend to focus on ore minerals such as sphalerite and galena. Therefore, there have not been extensive analyses for arsenic in iron sulfides in many of the MVT ore districts or trace-mineralized areas. However, a few studies on trace element contents in iron sulfides from the Ozark region have been performed. Wu et al. (1996) analyzed 80 pyrite and marcasite samples from the Viburnum Trend of the Southeast Missouri Lead District and found arsenic in concentrations of 2 to 900 ppm. Bhati and Hagni (1980) also analyzed iron sulfide minerals from this area, but did not publish results for arsenic. Hagni (1993) described the relatively rare occurrence of nickel-arsenic-sulfide ores from the Magmont-West ore deposit of the Viburnum Trend. Leach et al. (1995) list arsenic as a trace constituent in ores from the Northern Arkansas and Southeast Missouri MVT ore districts, but without abundances specified. 

The abundance of zinc in the Earth s crust averages 70 g ton . Zinc is a chalcophUic element like copper and lead, and a trace constituent in most rocks. Zinc rarely occurs naturally in its metallic state, but many minerals contain zinc as a major component from which the metal may be economically recovered. The mean zinc levels in soils and rocks usually increase in the order sand (10-30 mg kg ), granitic rock (50 mg kg ), clay (95 mg kg ) and basalt (100 mg kg ) (Adriano 1986, Malle 1992). Sphalerite (zinc blende, cubic ZnS) is the most important ore mineral and the principal source for zinc production. Smithsonite (ZnGOj) and hemimorphite (Zri4(Si207) (0H)2 X H2O) were mined extensively before the development of the froth-flotation process (Jolly 1989, Graf 2002). The main impurities in zinc ores are iron (1-14%), cadmium (0.1-0.6%), and lead (0.1-2%), depending on the location of the deposit (ATSDR 1994). 

In the Furado area there was no interruption in burial conditions caused by post-rift uplift, and the reservoirs remained at similar depths during this phase. Therefore, it is uncertain whether or not the mesogenetic constituents were precipitated during syn-rift or post-rift phases. Some C2 calcite, which engulfed and thus post-dated albite, chlorite, illite, quartz and trace amounts of pyrite, barite and sphalerite, is interpreted to have precipitated during this time interval. This C2 calcite is characterized by a chemical and isotopic composition similar to the carbonate cements formed during the syn-rift subsidence phase. 

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