Chalcophilic elements

Figure 15.1 Position of the chalcophilic elements in the periodic table these elements (particularly those in white) tend to occur in nature as sulfide minerals the tendency is much less pronounced for the elements in normal black type.

In the northern Yilgarn and surrounding areas, such as the Baxter deposit) chalcophile elements are enriched in groundwaters contacting with weathering sulfides (e.g., As, Mo, Ag, Sb, W, Tl, and Bi) and these may be more useful regional exploration tools than dissolved Au itself (Fig. 1). 

Occurrence. Copper is a typical chalcophilic element its principal minerals are sulphides, mostly chalcopyrite (CuFeS2), bornite (CusFeSyCujFeSj) and chalcocite... 

Occurrence. Thallium can be associated to heavy metals that occur in sulphidic ores (chalcophilic element behaviour) or to alkali metals in minerals such as car-nallite, sylvite, mica (the Tl+1 ion behaves as an alkali metal ion), or in true, but very rare, thallium minerals such as lorandite (T1AsS2), chalcothallite (Cu3T1S2). 

Goodfellow, W.D., Jonasson, I.R. Morganti, J.M. 1983. Zonation of chalcophile elements about the Howard s Pass (XY) Zn-Pb deposit, Selwyn Basin, Yukon. Journai of Geochemicai Expioration, 19 503-542. 

A sulfidic halo is characterized mostly by elevated S, Au, As and Sb. It extends further than suggested by previous alteration studies, and is defined by the development of disseminated hydrothermal pyrite and, to a lesser extent, arsenopyrite. Gold deposits of the Costerfield stibnite domain (i.e., Fosterville and Costerfield) can be differentiated from Au-As orogenic deposits by a greater primary dispersion of anomalous As and higher threshold values for Sb, as well as by the presence of slightly elevated concentrations of Hg (>0.01 ppm). Other chalcophile elements at variably elevated levels within the sulfidic alteration halo include Mo, Se, Bi, Pb and Cu. 

The most abundant mineral in aubrites is coarse-grained orthopyroxene (as it is in enstatite chondrites), and only a small amount of plagioclase is present. Aubrites are commonly brecciated, and several clasts of related basalt have been observed. The aubrites are depleted in siderophile and chalcophile elements relative to chondritic abundances,... 

Elemental abundances in CR2 chondrites normalized to the Cl composition and plotted in order of decreasing volatility from left to right. Lithophile elements are shown with open circles, siderophile elements with black circles, and chalcophile elements with gray circles. CR2 data from Kallemeyn etal. (1994). 

Bulk compositions of H, L, and LL chondrites normalized to Cl abundances. Elements are plotted in order of decreasing volatility from left to right. Lithophile, siderophile, and chalcophile elements are designated with open, black, and gray symbols, respectively. These diagrams reveal fractionation of these element groups among different ordinary chondrite classes. Data from Kallemeyn et al. (1989). 

As we learned earlier in Chapters 4 and 7, chondritic abundances can vary. Figures 11.9a and 11.9c show variations in lithophile elements, and Figures 11.9b and 11.9d illustrate variations in siderophile and chalcophile elements (all normalized to Cl chondrite abundances, and plotted in order of increasing volatility from left to right in each diagram) for the major classes of anhydrous meteorites. As is apparent in these... 

Compositional variations among chondrites, (a) Lithophile and (b) siderophile and chalcophile elements in ordinary (H, L, LL), enstatite (EH, EL), R, and chondrites. In (c) and (d), the same data are shown for anhydrous carbonaceous chondrite groups. Elements are plotted from left to right in order of increasing volatility. Lithophile elements are normalized to Cl chondrites and Mg, siderophile and chalcophile elements are normalized to Cl chondrites. Modified from Krot et al. (2003). 

Figure 12.17a shows lithophile element abundances, and Figure 12.17b shows sid-erophile and chalcophile element abundances in CM chondrites, normalized to Cl chondrites. Illustrated for comparison are the abundances in CO chondrites, which are the anhydrous carbonaceous chondrite group most closely allied to CM chondrites. As in other chondrites, the greatest differences are in volatile elements. The volatile and moderately volatile elements in CM chondrites are present at 50-60% of the abundances of the refractory elements. The volatile elements are primarily located in the matrix, and the matrix comprises 50-60% of CM chondrites. This implies that the matrix has essentially Cl abundances of all elements, while the chondrules and refractory inclusions have Cl relative abundances of refractory elements but are highly depleted in the volatile elements. The sloping transition in the region of moderately volatile elements indicates... 

Differences in the abundances of (a) lithophile and (b) siderophile and chalcophile elements, all normalized to cosmic (Cl chondrite) abundances, among altered carbonaceous chondrite groups. Normalizations as in Fig. 11.9. Modified from Krot etal. (2004). 

Goldschmidt (32) also introduced the concept of a geochemical classification of elements, in which the elements are classified on the basis of their affinities and tendencies to occur in minerals of a single group. The chalcophile elements are those which commonly form sulfides. In addition to sulfur, they include Zn, Cd, Hg, Cu, Pb, As, Sb, Se, and others. When present in coals, these elements would be expected to occur, at least in part, in sulfide minerals. Sulfides other than pyrite and marcasite have been noted in coals, but, except in areas of local concentration, they occur in trace or minor amounts. 

Goodarzi, F. and Swaine, D.J. (1993) Chalcophile elements in western Canadian coals. International Journal of Coal Geology, 24(1-4), 281-92. 

Most chalcophile elements (i.e, S and other elements with an affinity for S in nature such as Cu, As, Se, Cd, In, and W), boron, and the halogens are enriched in coal with respect to soil, and this accounts in part for their enrichment in emitted particles. Differences between eastern and western coals are apparent for many elements, especially the alkali and alkaline earth metals, As, and In. This accounts for some of the large plant-to-plant variability that we observe below. 

Unlike silicon and germanium, tin and lead belong to the family of chalcophile elements (according to the Goldshmidt geochemical classification), which have a high affinity to sulfur. In this connection the stability of the stannathiane Sn—S bond (in the Sn—S—Sn... 

Chalcophiles elements that tend to combine with sulfur. 

Yi, W., Halliday, A. N., Langmuir, C., Garcia, M., and White, W.M. (1996) Tellurium and cadmium in MORB and OIB and volatile chalcophile element fractionation in the Earth. Trans. Amer. Geophys. Un. 77, F810. 

From the study of complexes, Ahrland Chatt and Davies arrived at a classification scheme comprising A-type and B-type central atoms corresponding to lithophilic and chalcophilic elements. 

Chalcophile elements, tending to occur as sulfides or other chal-cogenides (e.g., Zn, Cd, As, Se) ... 

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