(Bloomberg) -- Two North Carolina mining operations that produce more than three-quarters of the world’s high-purity quartz, a material critical to the solar and semiconductor industries, have now been halted for almost a week due to Hurricane Helene.

Sibelco and Quartz Corp. both shut their operations on Sept. 26, the companies said in separate statements. It’s too early to say when production could restart, they said. 

The mines are near Spruce Pine, a small town an hour north of Asheville in North Carolina that’s one of the most important global suppliers of quartz. The two operations account for more than 80% of the world’s supply of commercial high-purity quartz, BloombergNEF said in a report last year.

The impact on the global chipmaking sector remain unclear, given semiconductor firms are adept at stockpiling essential components and the operations in North Carolina are expected to eventually resume. 

Infineon Technologies AG and Taiwan Semiconductor Manufacturing Co. — the world’s largest chipmaker — said they were keeping tabs on the situation but didn’t anticipate any significant impact to their operations for now.

There’s only about 20,000 tons a year of extremely high purity quartz produced at Spruce Pine, BNEF solar analyst Jenny Chase said in a note on Tuesday. It’s important to both the solar and semiconductor industries, because it’s used to make the inner layer in crucibles, she said, adding that a prolonged disruption in supply could accelerate the adoption of synthetic alternatives. 

The storm severely hit the community, which is struggling with flooding and power and communication outages, and the restart of operations is a secondary concern for now, the miners in Spruce Pine said in their statements.

--With assistance from Edwin Chan, Christina Kyriasoglou, Annie Lee and Jane Lanhee Lee.

(Updates with TSMC comment)

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