The workers were responsible for carrying out care and maintenance work at the mine.
"Employees are dissatisfied, as they have not received their salaries since February," the union said in a statement.
"In addition, it has come to light that life insurance has not been taken out for them."
Solidarity had notified Aurora's management of the employees' dissatisfaction in writing last week, but had not received any feedback yet.
"The trade union maintains that the company should take responsibility for these employees and their safety."
Gideon du Plessis, deputy general secretary of Solidarity, said these employees stayed behind to carry out essential maintenance at the mine.
As the last remaining employees of the mine's estimated 3000 were responsible for, among other things, pumping out contaminated mine water from the mine.
"The maintenance work that is done at the mine is crucial in order to protect the mine as an asset," the union said.
One individual persuading others to strike
"Should any of these employees be involved in an accident, they would not be compensated."
Du Plessis said the employees continued to work under extremely dangerous circumstances.
Solidarity said that in terms of the Compensation for Occupational Injuries and Diseases Act of 1993 (previously the Workmen's Compensation Act) the mine was required to take out the necessary insurance for its employees.
Du Plessis said the strike could have a negative impact on the environment and the mine itself.
"If the pumping out of contaminated mine water is not resumed this week, the Grootvlei Mine as an asset could be destroyed as a whole.
Aurora spokesperson Thulani Ngubane confirmed there were only 100 workers left at the Grootvlei mine and that the company had retained these workers to perform care and maintenance.
"Only one individual is persuading the others to strike," he added.
Ngubane said in view of the strike declaration, other workers would be employed to pump out water from the mine.
"The Grootvlei mine is a national asset. So they must understand that if they strike they could cause over 3 000 jobs to be lost in the future."
Ngubane said Aurora - whose managing director is Zondwa Mandela,
a grandson of Nelson Mandela, and chairperson Khulubuse Zuma is
President Zuma's nephew - would list on the JSE by the end of August,
thereby opening up a channel of funding from Swiss investment firm GEMS.
- Sapa