A North Carolina county imposed a 60-day mining moratorium on Friday, giving officials time to rework local regulations before Piedmont Lithium Inc applies for a necessary zoning variance.

Commissioners in Gaston County, west of Charlotte, unanimously approved a resolution that says the company "cannot be trusted without adequate local controls to protect the health, safety and welfare" of citizens.

Piedmont representatives could not immediately be reached for comment. The company's shares fell 1.3% in after-hours trading.

If developed, the mine would become one of the largest US sources of lithium for electric vehicle batteries. But officials have worried it could taint groundwater supplies and cause light and noise pollution, among other concerns.

Piedmont told an investment conference this week it expects state approval by mid-2022. County approval would be the next step.

Piedmont has said it intends to engage in blasting - common for open-pit mines - multiple times per day. That has fueled concerns the company could blast during overnight hours, potentially affecting roughly 500 homes near the mine site.

"It is abundantly clear that a mine of this size ... was never anticipated in your development regulations," Tom Terrell, an attorney the county commissioners hired to advise them on the Piedmont project, said at the 15-minute Friday meeting.

Piedmont has heavily promoted its mine to Wall Street for years, including hiring Academy Award-winning actor Morgan Freeman to narrate a nearly 3-minute promotional video.

The company last autumn signed a deal to supply Tesla with lithium sourced from North Carolina, sending its stock up tenfold, though the timeline to begin supply was pushed back indefinitely earlier this week.

Piedmont, though, only first approached county commissioners last month about its project. The delay has strained relations with the six-member board.