Caledonia Mining has lifted the resource base at its Blanket mine in Zimbabwe, 15km west of Gwanda.
The company added 222,000t of new inventory to the indicated resource category, in addition to a further 283,000t to the inferred resource category at its 49%-owned Blanket mine.
The addition has been made based on the diamond core drilling conducted at depth below the AR South Section over the past six months.
Caledonia upgraded inferred resources to indicated resources by continuing infill drilling at Blanket section.
Following this, 254,750t of Blanket Quartz Reef, No1 and No 2 ore bodies have been upgraded.
The combined total of new and upgraded indicated resources of 476,750t was in addition to the 3,472,000t of reserves and indicated following an upgrade carried out in May 2015.
The upgrade and addition represents a 14% rise in terms of tonnes and 19% in terms of contained gold.
Caledonia Mining CEO Steve Curtis said: "This upgrade reflects the company's increased focus on resource development at Blanket mine as we progress with the revised investment plan that will boost production levels from 2016 onwards.
"After the upgrade announced today, the division between Blanket's resource categories has improved to 62% in the measured and indicated category and 38% in the inferred category."
The Blanket mine was acquired by Caledonia from Kinross Gold with effect from April 2006 and operates at a depth of 750m below surface.
The mine produced 45,500oz of gold in 2013. It also holds brownfield exploration and development projects on the existing mine area, as well as its satellite properties.