Maricunga is less than 5% the size of the lithium-rich Salar de Atacama in northern Chile, but high-grade deposits of the battery metal makes it attractive to miners.
North American Lithium (NAL), backed by top battery maker Contemporary Amperex Technology, halted operations last year at its Quebec mine and obtained creditor protection in May.
Vale said its annual assets review of its base metals and coal business is still underway and further impairments charges that would also impact fiscal year 2019 cannot be ruled out.