Mexico is home to large potential reserves of lithium but most of it is in hard-to-tap clay deposits that are costly and technically difficult to mine.
Rio said the landslip had been expected based on geo-technical monitoring at the mine, and all personnel had been removed from the area in advance to ensure safety.
Peru's presidential front-runner is taking aim at copper mining firms' coveted tax stability agreements that freeze tariffs, and the plan could have an outsized impact on Chinese miners.
Moscow has been keeping a close eye on rising raw materials costs in the construction sector as part of efforts to keep domestic commodity prices stable.
Sibanye reported a 78% increase in first-quarter core profit last month, on the back of higher prices for metals, including gold, platinum, palladium and rhodium.