Xiangxi ore field, Yuanling Co., Huaihua Prefecture, Hunan Province, China

Proterozoic low-grade metamorphic rocks, comprising the Lengjiaxi group (base) with sandy, greyish green slates and locally phyllites, and the Banxi group (top), consisting of (a) the Madiyi Formation of red slates, locally interbedded with sandy rocks and sandstones, and (b) the Wuqiangxi Formation of sandy, greyish green slates, arkoses and sandstones. The Madiyi Formation is a very important host unit for gold deposits in northwestern Hunan.
Mines previously exploited in the Xiangxi orefield are Sujiaxi, Hongyanxi, Yuershan, and Upper Woxi (Shangwoxi), the latter three of which worked different ore blocks of the Woxi deposit. Xiangxi is the largest one, and is still being mined. The mineralization is controlled by the E-W striking Woxi thrust fault and by anticlines and synclines. At the fault, the Madiyi Formation dips under the younger Wuqiangxi Formation. To the southwest, the Lengjiaxi Group is disconformably overlain by the Madiyi Formation. The deposits occur as stratabound orebodies in red slates of the Madiyi Formation. The mineralization may be associated with a magmatic intrusion.

Ref.:
- Sixue Yang, Blum, N., Rahders, E., and Zhenru Zhang (1998): The nature of invisible gold in sulfides from the Xiangxi Au-Sb-W ore deposit in Northwestern Hunan, People's Republic of China. Canadian Mineralogist 36, 1361-1372.