Unrest has rippled across the gold- and platinum-producing regions that surround Johannesburg since  the police killed 34 miners at a platinum mine last month in Marikana, 80 miles northwest of here, in an effort to halt a violent, illegal strike by workers demanding that their wages be raised. The spreading turmoil is destabilizing one of the most important industries in Africa’s biggest economy.

In a speech to striking workers at a gold mine on Monday, Julius Malema, the firebrand former leader of the African National Congress Youth League, called for a national mining strike until wages for all miners were increased to about $1,500 a month, roughly double or triple what they take home now.

“Where are our leaders?” thundered Mr. Malema, dressed in a white shirt embroidered with the logo of the A.N.C., from which  he has been expelled , and a black beret. “Our leaders have sold out South Africa! Our leaders are sleeping with capital!”

Amid the turmoil,  Anglo American Platinum , which says it produces about 40 percent of the world’s newly mined platinum, announced Wednesday that it was shutting down its mining operations near Marikana because of threats against its workers.

“In light of the current volatile situation in the Rustenburg area, where our employees, who want to go to work, are being prevented from doing so and are being intimidated by the threat of violence, Anglo American Platinum has decided to suspend its operations,” the company said  in a statement .

Security guards on Wednesday fired tear gas at workers engaged in a wildcat strike at a gold mine in Carletonville, 50 miles southwest of Johannesburg. On Sunday, about 15,000 workers walked off the job at the mine, which is operated by Gold Fields.

The mine in Marikana where the killings took place, which is owned by  Lonmin , a company based in London, has been closed for more than a month since the company’s rock drill operators, who perform some of the hardest, most dangerous work, went on strike to demand higher wages.

Many of the strikers were members of a radical, breakaway union and had expressed dissatisfaction with the country’s largest union, the National Union of Mineworkers, which is part of the trade union federation allied with the governing A.N.C.

So far, the unrest has done little to dent South Africa’s economy. Neither its stock market nor its currency has suffered as a result of the strikes. Labor unrest is common in South Africa, though it is not usually this violent, said Frans Cronje, an analyst at the South African Institute of Race Relations , a research institution that counsels investors.

“South Africa has a background of conflict and instability and violence,” Mr. Cronje said.

But the strikes underscore the problems the country faces: the highest level of inequality of any large economy, according to some estimates; jobless rates that reach 50 percent among young blacks; and an education system churning out graduates ill prepared for what jobs are available. The A.N.C., which bills itself as the protector of the poor, is now seen by many here as too cozy with the owners of capital.

“The corporate world does not yet realize the seriousness of the social and economic inequalities that confront the country,” Mr. Cronje said. “They have felt very often that their political connections are insurance that can bail them out of the problem. But the biggest constituency is the people who do not vote. It does not help therefore to have an A.N.C. insider on your board.”

Mr. Malema, who was ejected from the A.N.C. this year for sowing discord within the party, has been visiting striking miners in what is widely seen as a bid to shore up his popularity and help push President Jacob Zuma out as president of the party. Known for his radical pronouncements advocating the nationalization of the country’s mines and the seizure of white farms without compensation, Mr. Malema is the subject of multiple corruption investigations into his vast and mysteriously acquired fortune.

Mr. Malema received a warm reception from striking gold miners, who waved ceremonial cudgels, marched and sang songs in his praise. One held up a sign reading “Juju for President,” using Mr. Malema’s nickname. But other workers were skeptical.

“He says that the mine bosses are using us, the politicians are using us,” said Vusi Tshomela, 28, a gold miner. “I think he is also using us.”