Sibelco and The Quartz Corp. shut down operations ahead of the arrival of Helene. One of the two companies that manufacture high-purity quartz used for making semiconductors and other high-tech products from mines in a western North Carolina community severely damaged by Hurricane Helene is operating again.Sibelco announced on Thursday that production has restarted at its mining and processing operations in Spruce Pine, located 50 miles (80 kilometers) northeast of Asheville.