The last gold miner is leaving the JSE's club of largest companies. When AngloGold Ashanti drops out of its Top 40, the Johannesburg exchange will be devoid of any producer of the precious metal that was the bedrock of South Africa's economy for more than a century and a cornerstone of its industrialisation.After a 74% plunge in the value of its stock since the beginning of 2012, the world's third-biggest gold producer will be excluded from the FTSE/JSE Top40 Index from December 21, the exchange said this week.BHP Billiton, which has no operations in South Africa, Anglo American and its platinum unit will be the only mining stocks in the gauge.Sasol uses the coal it mines to produce motor fuel.Gold output by South Africa, whose Witwatersrand Basin is the source of about a third of all bullion mined, slid at the fastest pace among the 10 biggest-producing countries in the past decade. Production halved over the period to about 145 metric tons last year as grades declined, shafts became deeper and operating costs such as labour and electricity rose at a faster pace than inflation.Gold mining in South Africa has been "permanently impaired", said Peter Major, mining analyst at Cadiz Specialised Asset Management. "We were the Silicon Valley of gold mining and took the rest of the world out of business. That is history now."For the world's ailing metals-mining industry to have any hope of a turnaround, more producers may have to go belly up, say mining analysts.Companies that dig up everything from gold to copper have failed to stem a prolonged collapse in mineral prices, mostly because not enough mines are closing. Years of increased output have created global surpluses just as slower economic growth erodes demand.China, the world's biggest metals user, has been mostly to blame for the price slump. The Asian country's economy is expanding at the slowest rate in a generation, curbing demand, just as new mines are coming into operation."We need to see supply cuts across these markets to try to bring them back into balance," said Colin Hamilton, global head of commodities research at Macquarie Group in London."It's either companies making the decisions themselves, or it comes through a full process of people dying very slowly." ..