Willsboro, on the east side of the park, is home to a unique mine and plant, one of the only domestic sources of wallastonite. Wallastonite is a mineral composed of calcium, silicon, and oxygen, with properties that make it useful in plastics, paints, ceramics, and adhesives. It was discovered and extracted near here, at the Fox Knoll mine, before anywhere else in the country. This site has been mined since 1943, originally by the Cabot Company, and produces around 100,000 tons of the material per year. The mine is now owned by Imerys, a global mineral company based in France, with historical roots in the Rothschild Family’s non-ferrous metal mines. The company has grown through acquisitions of other non-ferrous, performance, and specialty material mines, extracting corundum, feldspar, quartz, kaolin, talc, perlite, and bentonite. Imerys has 40 locations in the USA, but this is its only wallastonite mine in the country.