Most of the Sn mineralization worldwide is commonly associated with highly -fractionated granites, especially with those granites rich in volatile components such as F, Cl, Li and B. However, previous researches paid little attention to the volatile B. The giant Furong tin deposit, located in the middle part of Nanling Region, is of great significance in China. Axinite was found in skarn in this deposit for the first time, which provides an ideal opportunity to explore the role of volatile B during the formation of tin deposit. By means of detailed mineralogical, petrological and geochemical studies, the petrographic characteristics, crystal structures and chemical compositions of axinites from Furong were depicted, followed by a discussion on the relationship between the volatile B and granite emplacement, as well as tin mineralization in this area. The axinite from Furong deposit is lilac brown in color, massive in texture, hard, colorless and light yellow under microscope, with self-shaped wedge shape, high protrusion and low interference color, and intergrown with vesuvianite, fluorite, garnet and sphene. It was revealed that the axinite belongs to axinite-( Fe), with a general chemical formula of Ca-2.22 (Feo(0.52),Mn-0.41, Mg-0.13)(1.06) Al-2.11 B-0.72 Si-3.98 O-15.5. There are various B -rich minerals including axinite, tourmaline and ludwigite in the Furong deposit, indicating that the Qitianling granitic pluton is rich in boron. The enrichment of the volatile B in granite can reduce the magma viscosity, and increase the degree of magma differentiation, which helps the enrichment of incompatible elements like Sn in the residual melt during the magma evolution. Boron is also closely related to tin mineralization, since the B enrichment can facilitate the extraction of Sn from source rocks, improving the Sn concentrations in the primary magma. Like F and Cl, boron can form a complex with Sn, which is beneficial to the long-distance migration for tin; and they can be enriched in residual melt during magma evolution because of similar geochemical behaviors of B and Sn during the fractional crystallization, and these magmas are considered to be the sources of the mineralizing fluid responsible for tin mineralization. In addition, with the continuous discovery of B -bearing minerals in the Furong tin deposit, it indicates that there is a good potential for the prospecting of associated boron ores in the studied area.

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