Due to a quirk of geology, the purest quartz in all the world comes from the picturesque town of Spruce Pine, North Carolina. The mineral, created deep within the Earth when silicon-rich magmas cooled and crystallized some 370 million years ago, is essential to the production of computer chips and solar panels.
China, India, and Russia provide high-purity quartz as well, but what’s mined there does not match the quality or quantity of what lies beneath the Blue Ridge Mountains. With Spruce Pine among the scores of Appalachian communities reeling from Hurricane Helene, the sudden closure of quartz mines that have supplied chip manufacturers for decades has rattled the global tech industry. But this quartz is vital to the solar industry, too. And while industry experts expect companies to withstand the temporary closure of the town’s two mines, it highlights the precariousness of a clean energy economy that relies on materials produced at a single location — especially in a world of increasingly ferocious natural disasters.
Helene’s impact on Spruce Pine “absolutely lays bare the danger of having a monopoly in any part of the supply chain,” said Debra DeShong, head of corporate communications at solar manufacturer QCells North America. QCells, which manufactures photovoltaic panels in Georgia and is building an additional facility that will manufacture the components needed to assemble them, is evaluating whether the Spruce Pine mine closures will impact it.
The industry relies on quartz primarily to make polysilicon, a highly refined type of silicon that forms the sunlight-harvesting cells in most photovoltaic panels. But the quartz from Spruce Pine serves another purpose: It is used to make the crucibles in which molten polysilicon crystallizes into cylindrical or rectangular ingots. Those rods are cut into the solar wafers that are further processed to produce the cells within panels.
Forming solar ingots requires heating polysilicon to over 2,500 degrees Fahrenheit. Only the highest purity quartz sand provides the thermal stability needed to create the crucibles capable of enduring such heat, and the best of it is found in western North Carolina.
“Spruce Pine is a very unusual quartz deposit and it is incredibly pure,” said Jenny Chase, the lead solar analyst at energy consultancy BloombergNEF.
BloombergNEF estimates that Spruce Pine supplies more than 80 percent of the ultra-pure quartz sand used to manufacture crucibles for both the solar and the semiconductor industry, as well as for optical and lighting applications. (There isn’t any public data on how much of the town’s quartz is used by each sector, but BloombergNEF estimates that in China, the world’s leading producer of photovoltaic panels, 80 percent of the high-purity quartz it uses goes into solar applications.) Spruce Pine dominates this market and supplies nearly all of the material that lines the inside of solar crucibles, which come in direct contact with molten silicon. There, purity is particularly important for ensuring high ingot yields and long crucible lifespans.
The amount of quartz required to support solar crucible production is fairly small. Chase says that Spruce Pine produced about 20,000 tons of high-purity quartz sand last year — more than enough to satisfy the demands of the solar industry. That same year, global polysilicon production stood at 1.52 million metric tons. Producing that much polysilicon likely required about 3 million metric tons of quartz, according to Chase. All of which is to say, Spruce Pine is, she said, “quite a small cog” in the solar supply chain.
Still, a small cog can become a big problem if there are no contingencies when it breaks down. But Chase suspects that most crucible manufacturers — an industry based largely in East Asia — have stockpiles of high-purity quartz. May Haugen, who leads communications at The Quartz Corp, a Norwegian company that produces high-purity quartz sand at Spruce Pine, confirmed this in an email to Grist.
“The Quartz Corp operates in long value chains where everybody has learnt through COVID the importance of sizable safety stocks,” Haugen wrote. “Between our own safety stocks, which are built in different locations, and the ones down in the value chain, we are not concerned about shortages in the short or medium term.”
In preparation for Hurricane Helene, The Quartz Corp halted all mining operations in Spruce Pine on September 26. So did the Belgian firm Sibelco, the town’s other producer.
It is unclear when either company will resume mining: In an October 2 statement, The Quartz Corp wrote that while its plants do not seem to have been seriously damaged by the storm, it is still “too early to tell” when they will reopen, “as this will also depend on the rebuilding of local infrastructure.” In an October 4 statement shared with Grist, Sibelco wrote that its facilities appear to have sustained “minor damage” and that the company hopes to “restart operations as soon as we can.”
“Our dedicated teams are on-site, conducting cleanup,” the statement noted. “Our final product stock has not been impacted.” The company declined to say how the hurricane could impact its plan to double production capacity in Spruce Pine by 2025.
Even if both mines remain shuttered for months, the solar industry could adapt, Chase said. The Japanese firm Mitsubishi Chemical Group manufactures high-purity synthetic silica for the semiconductor industry, and the material meets the standards required for solar crucibles, according to Chase.
However, production would need to ramp up. Mitsubishi Chemical Group representative Kana Nuruki told Grist in an email that the company currently does not have enough synthetic quartz to support the solar industry, and what it does produce is “considerably more expensive” than the real thing.
Paying a premium for synthetic quartz would be a challenge for the price-sensitive solar industry, Chase said. “But if it had no choice, it would do it.”
Developing alternative supplies of high-purity quartz, even ones that cost more, could help fortify the solar supply chain against the next climate-fueled disaster. “As solar becomes a larger piece of our electrification, it’s going to be increasingly important that we ensure we have a stable supply chain,” DeShong of QCells said.
Still, manufacturing both semiconductors and solar panels in the U.S. is a key priority of the Biden administration, and it seems unlikely that Washington will want to see a critical cog in both supply chains move overseas. A spokesperson for the U.S. Department of Energy told Grist that the agency “is closely monitoring Hurricane Helene’s effects [on] the supply chain,” while “advancing efforts to maintain the stability of America’s energy systems.”
Spencer Bost, executive director of the community development organization Downtown Spruce Pine, said that quartz-mining operations are the largest private employer in the county and restarting it quickly is “very important from a local economy perspective.” If the federal government cares about building clean energy in America, Bost said, “we have all the stuff here.”
“We have the people who need the jobs here,” he added.
