More elaborate analysis [144,146] yields the same values of the energy barrier values of 3.05 [+ or -] 0.10 eV between the top of the VBs in InSb and GaSb and the bottom of the [Al.sub.2][O.sub.3] CB, indicating that in both antimonides the top of the VB is shifted by =0.4 eV with respect to arsenides
and by [approximately equal to] 1 eV as compared to phosphides of the same metals.
The primary ore minerals in the Bou Azzer district are chiefly cobalt, nickel and iron arsenides, copper sulfides, and native gold and molybdenite--Bou Azzer is also known to mineral collectors as the source of the world's finest crystal specimens of the ore species skutterudite and gersdorffite.
Vein 59 has yielded gray-green, thick-tabular crystals of annabergite, some with a yellowish patina, in fan-shaped and spherical groups in a quartz-rich rock with metallic gray nickel arsenides. These assemblages also contain nickelaustinite.
The PGE mineralization is very fine-grained (less than 20 microns) and comprised of tellurides, telluro-bismuthides, stannides, stibnides and arsenides
These sheaves may be loose, or may make jumbled clusters without matrix, or may rise at all angles from a dense black matrix of ore sulfides and arsenides
(recall that the world's best skutterudite occurs at Bou Azzer, too).
Associated primary metallic ores are massive and disseminated cobalt and nickel arsenides
(mostly clinosafflorite and rammelsbergite, identified by X-ray diffraction and electron microprobe analysis) and copper sulfides (mostly chalcocite) in a gangue of dolomite, coarse tabular barite and calcite.
The significant presence of lead sulfoantimonides and arsenides
(in particular guettardite, robinsonite, zinkenite and boulangerite) in the Seravezza marble is in contrast to their virtual non-existence in the Carrara marble.
Although most five-element deposits display similar geological characteristics such as Co-Ni-Fe arsenide
and sulfarsenide minerals occurring with native silver and bismuth in a gangue of carbonate ([+ or -] silicates), the individual deposits may also display distinct differences, such as host lithology, age, tectonic setting and igneous affinity.