IOTA is not actually mined like Bitcoin and Ethereum are. When The IOTA project was launched, the entire token supply was immediately issued to participants in the crowd sale. There is no need to mine IOTA because transactions are verified by network participants when new transactions are added to the network. Before a node adds a new transaction to the network, it verifies another two transactions. This means there are no fees and no need to pay miners by issuing new tokens.