Turquoise Hill Investors Sue Over Problems With Mongolian Mine

Turquoise Hill Resources Ltd. misled investors about whether progress on the Oyu Tolgoi copper-gold mine in Mongolia was proceeding as planned, a would-be class suit filed in federal court in New York says.

The company, parent Rio Tinto PLC, and related entities didn’t disclose “underground stability issues that called into question the design of the mine, the projected cost and timing of production,” according to the complaint filed in the U.S. District Court for the Southern District of New York.

Turquoise Hill also misled investors as to whether “publicly disclosed estimates of the cost, date of completion and dates ...