Members of the National Union of Mineworkers (NUM) in the gold sector will down tools on their night shift on Tuesday, the union said.
"The night shift is dependent on the mine, but it generally starts between 4pm and 6pm in the afternoon. Those members expected to report for duty then will not do so," NUM spokesman Lesiba Seshoka said.
Employers in the gold mining industry were issued with a strike notice by NUM on Friday.
On Monday, Seshoka said the union which claims to represent at least 80,000 workers in the industry, had heard rumours about a lock-out by the mining companies but this had not been confirmed.
The union rejected the final pay offer made by the Chamber of Mines.
Gold mining companies, represented by the chamber, offered a basic increase of 6.5 percent for category four and five employees, including rock drill operators.
An offer of six percent on the basic wage was made to category six to eight, as well as to miners, artisans, and officials.
In addition, accommodation allowances would be increased in accordance with the consumer price index.
The gold mining companies are AngloGold Ashanti, Gold Fields, Rand Uranium, Harmony Gold, Evander Gold, Sibanye Gold, and Village Main Reef.
The union is demanding R7000 a month for surface workers and R8000 a month for underground workers.
Charmane Russell, spokeswoman for the gold producers, had said the employers wanted to avoid industrial action.
"Negotiations and discussion have continued and will continue. Not reaching a settlement is not an option for the industry," she said.
"Our aim is to avoid industrial action, because industrial action is costly."
At this stage, talks of a lock-out were just rumours but the possibility remained, said Russell.
"Regulations provide the opportunity for employers to lock out. Obviously in considering all options we will consider that as well."
Trade union Solidarity, which claims to represent close to 10,000 workers in the industry, has asked the chamber for more time to consult its members about the new wage offer.
"So far, it seems we have 40 percent support for the strike and 60 percent against it," general secretary Gideon du Plessis said on Monday.
Solidarity was waiting to see if employers locked workers out in response to the NUM's strike.
"This will automatically mean that no services will be rendered and the mine will start flooding," Du Plessis said.
The union was also waiting for a revised offer.
Du Plessis said the union had instructed its members not to do the work of NUM members who were on strike.
"This is now the time when a lot of bilateral talks take place... We are hoping to engage with the chamber this week," he said.
Last week, Solidarity said it could settle for an 8.3 percent wage increase.
Trade union Uasa, said to represent close to 3000 workers, has accepted the final wage offer made by the chamber.