Abstract:

Greisen-vein  type  tin deposits are  the most  important mineralization  type  in Huashan granite, Guangxi, South China:
The Huashan granite is an oxidized-type granite. In this granite body the element tin predominantly exists as Sn4+
 in primary tin-
bearing minerals, such as biotite, amphibole,  titanite, rutile,  ilmenite and cassiterite. Based on the comprehensive mineralogical
study, we  recognize  that greisenization developed  through  interaction of  the medium-fine-grained biotite granite with a  residual
magmatic fliud formed by adequate differentiation and evolution. At the early stage of alteration, the tin in the primary tin-bearing
minerals was  leached out by magmatic  fliud, and entered  into  fluid or secondary mineral phases, such as  rutile, muscovite etc.
to accomplish  the  first concentration. Then, at  the  later stage of alteration,  the mineralizing  fluid was able  to  redissolve earlier
precipitated  tin-bearing minerals, and  tin entered  into mineralizing  fluid  to accomplish  the second concentration. Tin dissolved
in fluid combined with ligands, such as F-
, Cl
-
 etc. to form stable complexes and transported. During greisenization, there was an
increase  in pH, a decrease  in  temperature and a decrease  in  ligand concentration,  the stabilities of  tin complexes  in  fluid were
dropped down, and then the  tin  mineral deposits were formed

Key words: Huashan, granite, greisenization, tin mineralization, mineralogy