AMCU members went on a strike 11-weeks ago at Anglo American Platinum, Impala Platinum and Lonmin, demanding a more than doubling of monthly wages to 12,500 rand.
"We opened a strike fund in pursuance of a living wage for our members... we want as much money as we can raise," AMCU President Joseph Mathunjwa told reporters in Pretoria.
Mathunjwa declined to say if union funds had been depleted, but said the money would be used to "sustain" AMCU members as they were on strike under the "no work, no pay" principle.
The strike fund, which was opened on Monday, currently held 1 million rand from AMCU and 50,000 rand from the union leaders and other members, he said.
The strike is costing Africa's most developed economy billions of rand in company revenues and salaries. It is also a headache for President Jacob Zuma and the African National Congress, three weeks away from a national election.
There is no end in sight for the strike as government-brokered talks have so far failed to seal an agreement between the unions and platinum producer, who say they cannot afford to meet the wage increase.
Mathunjwa said the employers and the unions met last week to discuss AMCU's demand. He said the companies were expected to give a response following the talks.