SPRUCE PINE, N.C. (AP) -- Two North Carolina facilities that manufacture the high-purity quartz used for making semiconductors, solar panels and fiber-optic cables have been shut down by Hurricane Helene with no reopening date in sight.

Sibelco and The Quartz Corp both shut down operations in the Appalachian town of Spruce Pine on Thursday ahead of the storm that swept away whole communities in the western part of the state and across the border in East Tennessee. The town is home to mines that produce some of the world's highest quality quartz.

With increasing global demand, Sibelco announced last year that it would invest $200 million to double capacity at Spruce Pine.

Since the storm, the company has simply been working to confirm that all of its employees are safe and accounted for, according to a statement, as some were "unreachable due to ongoing power outages and communication challenges."

"Please rest assured that Sibelco is actively collaborating with government agencies and third-party rescue and recovery operations to mitigate the impact of this event and to resume operations as soon as possible," the company wrote.

The Quartz Corp wrote that restarting operations is a "second order of priority."

"Our top priority remains the health and safety of our employees and their families," the company wrote.