Investec has downgraded its rating for South Africa-focused miner Aquarius Platinum from 'hold' to 'sell', saying that the company's first-quarter financials on Thursday 'reflect a business which is still struggling'.The company said that underlying earnings totalled $6.3m in the three months to September 30th, up from $1.6m the year before but down $4m quarter-on-quarter due to higher costs and lower recoveries at its Kroondal project near Johannesburg. While group attributable production increased by 9% to 84,504, the average platinum group metal (PGM) basket price fell by 3% in dollar terms.Investec said that production volumes suggest an in-line start to the year, "although this was delivered at higher costs than anticipated at Kroondal". It pointed out that this is traditionally a relatively strong quarter for South Africa PGM producers.The broker has now reduced its long-term platinum price forecast from $2,090 an ounce to $1,900 an ounce, causing its earnings per share estimates for Aquarius to fall from 5.8 cents to 5.0 cents for the year ending June 2014.As such, the target price has been cut from 48p to 42p."The share have crept up from 42p since August. Given that the group has revealed a reduced cash position now that Mimosa is accounted for separately, and that the operating environment continues to be challenging, we see scope for the shares to retreat."The stock fell 1.32% to 46.88p on Thursday morning.BC