Due to a quirk of geology, the purest quartz in the entire 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 about 370 million years ago, is essential for the production of computer chips and solar panels.
China, India and Russia also supply high purity quartz, but what is 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 had supplied chipmakers for decades rattled the global technology industry. But this quartz is essential for the solar industry also. And while industry experts expect companies to resist the temporary closure of the town’s two mines, it highlights the uncertainty of a clean energy economy which rely on materials produced in a single location – especially in a world of increasingly severe natural disasters.
Helene’s impact on Spruce Pine “absolutely exposes 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 and is Georgia-based photovoltaic panels building an additional facility which will manufacture the components needed to assemble it, is evaluating whether the Spruce Pine mine closures will affect it.
The industry relies mainly on quartz to make polysilicona 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 blocks. Those rods are cut into the solar wafers that are further processed to produce the cells inside panels.
Formation of sun blocks requires heating of polysilicon to over 2,500 degrees Fahrenheit. Only the highest purity quartz sand provides the thermal stability needed to create the crucibles that can withstand such heat, and the best of these are found in western North Carolina.
“Spruce Pine is a very unusual quartz deposit and it’s incredibly pure,” said Jenny Chase, the principal 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 semiconductor industries, as well as for optical and lighting applications. (There is no 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, providing almost all of the material that lines the inside of solar crucibles, which come in direct contact with molten silicon. There purity is particularly important to ensure high ingot yields and long crucible life.
The amount of quartz required to support solar crucible production is quite small. Chase says that Spruce Pine produced about 20,000 tons of high purity quartz sand last year – more than enough to meet the demands of the solar industry. the same year, global polysilicon production stood at 1.52 million metric tons. Producing that much polysilicon probably required about 3 million metric tons of quartz, according to Chase. All that to say, Spruce Pine is, she said, “quite a small cog” in the solar supply chain.
Still, a small gear can become a big problem if there are no contingencies when it breaks. But Chase suspects that most crucible manufacturers — an industry based primarily in East Asia — have stocks 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 everyone has learned through Covid the importance of significant safety stocks,” Haugen wrote. “Between our own security stocks that are being built in different places and those at the bottom of the value chain, we are not worried 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 26th. So does the Belgian firm Sibelco, the town’s other manufacturer.
It’s unclear when either company will resume mining: In an Oct. 2 statement, The Quartz Corp wrote that while its plants don’t appear to have been seriously damaged by the storm, it’s still “too early to tell.” when they will reopen, “as it will also depend on the rebuilding of local infrastructure.” In an Oct. 4 statement shared with Grist, Sibelco wrote that its facilities appear to have sustained “minor damage” and that the company hopes to “resume operations as soon as possible.”
“Our dedicated crews are on site and cleaning up,” the statement said. “Our final product inventory has not been affected.” The company declined to say how the hurricane might affect its plan to double production capacity in Spruce Pine by 2025.
Even if both mines remain closed for months, the solar industry can adapt, Chase said. Japanese firm Mitsubishi Chemical Group produces high-purity synthetic silica for the semiconductor industry, and the material meets the standards required for solar crucibles, according to Chase.
However, production will have to increase. Mitsubishi Chemical Group representative Kana Nuruki told Grist in an email that the company currently doesn’t have enough synthetic quartz to support the solar industry, and what it does produce is “significantly more expensive” than the real thing.
Paying a premium for synthetic quartz will be a challenge for the price-sensitive solar industry, Chase said. “But if it had no choice, it would.”
Developing alternative supplies of high-purity quartz, even those that cost more, could help shore up the solar supply chain against the next climate-driven disaster. “As solar becomes a bigger part of our electrification, it’s going to become increasingly important that we ensure we have a stable supply chain,” said QCells’ DeShong.
Yet both produce semiconductors and solar panels in America is a key priority of the Biden administration, and it seems unlikely that Washington would want to see a critical cog in either supply chain overseas. A spokesperson for the US 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 Pinesaid that quartz mining is the largest private employer in the country 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 work here,” he added.
