密坑山锡矿田位于江西省会昌县西南约40km处。该区为一晚中生代破火山,火山岩为上侏罗统鸡笼嶂组流纹质凝灰熔岩及火山碎屑岩,火山口周围环状及放射状断裂发育,火山口中心为浅成相的密坑山似斑状钾长花岗岩中央岩株侵入体所充填。上世纪80年代以来,在该岩体与流纹质凝灰熔岩的 Mishan Shan tin ore field is located in Jiangxi Province Huichang County, about 40km southwest. The area is a late Mesozoic caldera, the volcanic rocks are rhyolitic tuff lavas and volcaniclastic rocks in the Upper Jurassic cages, with ring-shaped and radial ruptures around the crater, Pit Hill like plagioclase potassium granite central rock invaded by the body filled. Since the 80s of last century, the rock mass was lava with rhyolitic tuff