In answers to questions from MPs in parliament, local media reported Ramaphosa said it was tempting to think the nationalisation of mines could profit the state, but it could have the opposite effect.
"Mining is an industry that is not for sissies," he said.
Ramaphosa pointed out mining was an expensive practice subject to commodity price volatility. This meant the country could end up paying to keep unprofitable mines open.
"You could be pouring money down the drain," he said.
"Sometimes there are years of drought and years of boom. Mining, in the most part, can go bust, or have great years of boom."
South Africa's developmental state will be subject to those processes, he said, adding that the EFF should do its research and talk to people with mining experience, such as Gwede Mantashe, the recently appointed minister of mineral resources.
Mantashe, once a miner himself, spent many years at the National Union of Mineworkers and was also the first trade unionist to be appointed to the board of a listed mining company (Samancor) in South Africa in 1995.
Ramaphosa himself has been on the union and mine-boss side of the industry.
