Sumitomo Metal Mining Co. has found a new gold bed at the existing Hishikari gold mine in Isa, Kagoshima Prefecture, estimated at 30 tons with a market value of ¥130 billion.
The company will start digging a tunnel to the bed next month with the aim of starting the extraction in 2018, it said Tuesday.
It will have to pump out hot spring water, and the overall effort will cost ¥3.2 billion.
The company has produced about 200 tons of gold from the Hishikari mine since 1985. The new vein is deeper than any of the beds tapped so far.
The mine is estimated to hold a further 150 tons of gold, the Sumitomo unit said.