The $3.15 billion project will tap into the world’s largest and highest grade deposit of polyhalite, used as a fertilizer, inside the North York Moors National Park.
Prices for the precious rocks have fallen almost 12% in the past year, amid weakening diamond jewellery demand from China, the second largest consumer after the U.S.
According to research house Wood Mackenzie, the need for investment is becoming desperate in zinc and lead and will be a major issue in the copper sector in the next few years.