Figure 3

Main alteration types and relative positions within the Weilasituo Sn-polymetallic deposit. (a) Schematic sketch of the quartz porphyry intrusion. Lettering on solid black background shows schematically the sampling positions of specimens shown in (b–f). (b) Light sky-blue quartz porphyry with amazonite (K-feldspathization). (c) Albite alteration of quartz porphyry with abundant snowball-structured quartz phenocrysts. (d) Greisenization at the top of the quartz porphyry body. (e) Quartz porphyry in contact with the stockscheider. (f) Montmorillonite altered wall rock. (g) Chloritized wall rock. Ab–albite, Am–amazonite, Apy–arsenopyrite, Cst–cassiterite, Chl–chlorite, Fl–fluorite, Qz–quartz, Sme–smectite, Znw–zinnwaldite (rock-forming mineral abbreviations⁷⁹).