Yaogangxian Mine

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Tungsten-tin deposit in the contact aureole of the Mesozoic Yaogangxian composite pluton (consisting of coarse-grained biotite granite, fine-grained porphyritic granite, and quartz porphyry), which intruded into Cambrian-Devonian sediments (mainly sandstones) and Jurassic limestones. The mine field covers an area of about 4 x 2.5 km and includes two large deposits of a distinct type and mineralization style:

(1) The Yaogangxian quartz vein-type tungsten-tin deposit with minor greisen-style mineralization, which has been mined since 1914. The veins are hosted in the biotite granite phase of the Yaogangxian pluton and in its western and northern contact zone. They trend NW to NNW and are grouped in three vein swarms (ore blocks), from west to east: Yangmeiling, Luchangping, and Hamashi. The ore bodies contain minor copper, silver, lead, zinc and bismuth minerals. They are strongly zoned both vertically and horizontally. Another group of veins with economic tungsten grades was recently discovered at depth southwest of the Yangmeiling ore block (Yan et al., 2010).
(2) The Heshangtan skarn-type tungsten-tin deposit, which was discovered in 1947, explored during the 1950s and has been mined since the early 1960s. The ore bodies are hosted in Devonian sandstone and skarnized slate in the eastern contact zone of the Yaogangxian pluton. They contain significant amounts of associated silver ores.

The mineral list includes all species reported from both deposit types, since there is often no clear distinction made in papers on the Yaogangxian mine, especially in western publications. Apart from the obvious differences between quartz vein and skarn mineralization, there also are some notable differences in the ore mineral assemblages:

(1) Except for bismuthinite, which has been reported from the skarn ore bodies (Xu, 1957) and as a microscopic constituent of greisen inclusions in the host granite (Zhou et al., 2013), bismuthiferous minerals have only been reported from the vein-type ore bodies.
(2) Most of the silver minerals and most of the sulfosalts have only been reported from the skarn ore bodies.
(3) All wolframites from the vein-type ore bodies have a significant excess of manganese over iron and are thus hübnerites (Chen, 1981).

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