Year-on-year revenues at Africa-focused miner Caledonia Mining jumped by 152% in the first quarter, as gold production more than doubled.Revenues surged from C$4.46m (£2.84m) in the first three months of 2010 to C$11.23m (£7.15m) this year, as the average achieved price of gold jumped 26% to US$1,397 per ounce."I am very pleased to report a strong first quarter performance for 2011. The increased production coupled with the continued strength in the gold price and a reduction in Blanket's [its Zimbabwean gold mine] cash cost resulted in a substantial improvement in Caledonia's profitability and cash generation," said president and chief executive officer Stefan Hayden.During the period, Caledonia produced 7,322 ounces of gold, up 17% on the fourth quarter of 2010 (6,235 ounces), and 134% higher than the amount produced in the same period the year before (3,129 ounces).At the same time, the firm was able to scale back the cash cost per ounce of gold produced by 20% over the year to US$648, compared with US$807 previously.Pre-tax profit swelled to C$3.04m, from C$0.11m, while earnings per share increased to 0.38 cents, from 0.02 cents.---BC