Solidarity has threatened to bring Lonmin's operations to its knees if the company does not reconsider its decision to revoke Amcu's recognition.
The threat follows an agreement Lonmin signed with the Association of Mineworkers and Construction Union (Amcu) last week.
According to Solidarity, it has already engaged in talks with other trade unions, including the National Union of Mineworkers (NUM), regarding possible joint labour action.
"The recognition agreement between Lonmin and Amcu includes a bizarre clause according to which a trade union whose recognition has been suspended can regain recognition if its members participate in a disruptive strike," the union said on Monday.
"The new recognition agreement requires trade unions to strike disruptively if they want to get recognition,"
said Gideon du Plessis, general secretary of Solidarity. "Solidarity's members are the skilled employees who kept the mine going in the past during the unrest fuelled by Amcu. Lonmin, however, has decided to reward unrest and to penalise responsibility."
Up until now, Lonmin’s workforce was divided into two bargaining units: one that represented lower-level workers, where Amcu holds a 75% majority; and another smaller bargaining unit of higher-level workers, who are largely represented by the National Union of Mineworkers, Uasa and Solidarity, which amounted to 23%.
The new recognition agreement with Amcu collapses the two into one, automatically making it the majority union overall and the only one with enough representation to have organisational and bargaining rights.
At the time, Solidarity said it felt betrayed and openly appealed to Lonmin to reassess its "ill-considered decision".
Solidarity referred the matter to the Commission for Conciliation, Mediation and Arbitration on Monday afternoon. "We now wait for a conciliation date, and if at that conciliation meeting we fail to reach agreement … a certificate will be issued which will allow us to go on a protected strike," du Plessis told the Mail & Guardian.
According to Du Plessis, Solidarity has started obtaining a mandate from its members regarding the possibility of a strike.
"A strike will be the last resort, however, as it could have devastating consequences."
Solidarity estimates such a strike would cost Lonmin around R60-million a day in production losses. "The irony is that Amcu members will lose about R18-million in bonuses if Solidarity and the other trade unions' members strike for just one day," said du Plessis.
Lonmin could not provide official response as it had not yet been notified.