Figure 4
Photomicrographs of minerals from the Weilasituo deposit. (a) Snowball-structured quartz phenocrysts. (b) Qz + Znw + Sp vein in quartz porphyry. (c) Cassiterite associated with sphalerite has advanced white interference color. (d, e) Cassiterite has regular zonal structure with a dark core and brightly colored rim. (f) Association of sphalerite, chalcopyrite, pyrrhotite and arsenopyrite from the Weilasituo Cu–Zn deposit. (g) Exsolution of chalcopyrite in pyrrhotite along crystallographic axes. (h–k) BSE images of mica associated with fluorite from the wall rocks in Weilasituo Cu–Zn deposit indicating growth zones in the early stage (h) and strong hydrothermal alteration in later stages. (l) SEM–EDS map showing loss of Fe during hydrothermal alteration (the chemical formulae of mica may change from K(AlFe2+Li)(Si3Al)O10(OH,F)2 to KAl2(Si3Al)O10(OH,F)2). Apy–arsenopyrite, Ccp–chalcopyrite, Cst–cassiterite, Fl–fluorite, Pl–plagioclase, Po–pyrrhotite, Qz–quartz, Sp–sphalerite, Toz–topaz, Znw–zinnwaldite.
