Indonesia's finance chief said a deal to buy a controlling stake in a massive copper mine in the country could be resolved by the end of this year.

In August, U.S.-based Freeport-McMoRan agreed to sell a 51 percent stake in the Grasberg mine in exchange for licenses to operate the massive copper and gold pit until 2041. The agreement is meant to end public anger over foreign ownership of Indonesia's biggest copper asset, which is also the world's second-biggest copper mine.

Speaking with CNBC, Indonesian Finance Minister Sri Mulyani Indrawati said the agreement has held so far, and it could be executed before 2018.

"I think we will continue making our best effort to make it hopefully even earlier than that. But we will try to do our best and I think the communication is good," she said Wednesday in Washington D.C.

On valuing the 51 percent stake her government agreed to buy, she said the starting point was fair: "I really believe that both parties have a strong intention and willingness to come up with a good agreement which is benefiting Indonesians and Freeport."

As part of the deal, Freeport-McMoRan will also build a second smelter in Indonesia and plans to invest between $17 billion and $20 billion in Grasberg between now and 2031.