Indium and germanium in the structure of sphalerite: an example of coupled substitution with Copper

摘要: The distribution of indium in sphalerite from hydrothermal veins the Saint-Martinla-Sauvete district (Loire, France) was studied by microprobe. Several hundred analyses were carried out. Sphalerite, devoid chalcopyrite inclusions, exhibits an oscillatory zoning which can be related to variation minor-element concentrations. Indium (up 1.05 wt. %) is positively correlated with copper, and Cd Fe. these two pairs elements antithetic within (110) growth zones. In Cu show a very complex some twinned crystals are preferentially concentrated {111} A diffusion/growth velocity ratio evoked explain this behaviour. From core rim concentration decreases that (and Cu) increases. This increase corresponds development faces, become progressively more prominent. slope regression line calculated values corresponding < 0.4 % subparallel (Cu/In)at = 1. indicates substitution mechanism Cu(I) + In(III) ⇄ 2 Zn(II). However, generally higher than required equation. Cuex rises toward crystals; Cu-rich In-free zones exist crystals. above CuS solubility limit sphalerite. It suggested Fe(III) could assume local charge balance Cu(I). hypothesis compatible rise late crystallization respect observed deposits. Consequently, incorporation Saint-Martin-la-Sauvete governed following equation: M(I) M(III) Zn(II), where Cu; In,