"He was hacked with a panga after he and his colleagues came out of an evening shift on Sunday," mine spokesperson Barnard Mokwena said on Monday.
Several others workers were injured. They had been treated and discharged from hospital.
Mokwena said a group of men armed with iron rods and pangas attacked the employees as they came out of the mine shaft.
The company was shocked by the violence and would meet the provincial police commissioner Lieutenant General Zukiswa Mbombo later on Monday.
"We need police intelligence on this as we do not know who these killers are, or where they come from," Mokwena said.
Two security guards were killed when their car was set alight at the mine on Sunday. Four workers were shot and wounded on Friday and Saturday.
Mokwena said the company was still trying to inform their families.
Police said the killings were linked to ongoing conflict between two unions which had members on mines in the area.
Members of the National Union of Mineworkers (NUM) and the Association of Mineworkers and Construction Union (Amcu) were reportedly fighting for control of local mines.
Amcu secretary Jeff Mphahlele said his union did not encourage violence and was not responsible.
"We have been recruiting across the country and have at times been met with resistance. Four of our members were shot at in Marikana, but they never retaliated," he claimed.
NUM spokesperson Lesiba Seshoka said the police knew who the perpetrators were.
"They are actually aware of who is responsible for this violence. The police are part of the problem."
Seshoka said the union would ask Police Minister Nathi Mthethwa to intervene.
Police spokesperson Brigadier Thulani Ngubane said no arrests had been made yet.
"We are keeping an eye on the situation."
In February, the two unions clashed over membership at Impala Platinum's mines. – Sapa