That was 13% up on the previous quarter and the highest level of concentrate for nearly four years.

Rambler said year-to-date mill throughput of 211,090t at an average 1.36% copper and 0.59gpt gold had it on tracked for its guided 400,000-450,000t at 1.3-1.5% copper. SP Angel in London said average gold grades were below the guidance range of 0.7-0.9gpt, but "we estimate that precious metals represent only around 15% of overall revenue".

"Given the productivity improvements in the mine, which have provided access to better grade material in both the Lower Footwall Zone and the Ming massive sulfide deposits, we are now turning our attention to increasing the overall feed grade delivered to the mill," Rambler CEO Andre Booyzen said.

A new tailings disposal facility, capable of sustaining processing rates "in excess of 1,400t/day" is expected to be operational ahead of schedule by the end of this month, giving Rambler scope to continue its continuous improvement program. The mill achieved a new one-day record throughput of 1,493t on July 22.

"This last quarter's mine and mill performance has demonstrated effectiveness of the focus on continuous improvements that were started in late 2018 and still continue," Booyzen said.

"We will keep improving mining production and the average grade of ore produced so that saleable copper production continues to increase."

Rambler shares (LSE: RMM) got to 1.74p this week after opening Monday at 1.35p. After dipping to 1.27p Thursday the shares were up 7.8% Friday at 1.37p, capitalising Rambler at about £20.35 million.