Sodium fluoride comes from two main places: it occurs naturally as a rare mineral called villiaumite, and it’s manufactured industrially by reacting hydrofluoric acid with sodium carbonate or sodium hydroxide. Most of the sodium fluoride people encounter, whether in toothpaste, drinking water, or industrial products, is synthetically produced. A large share of the fluoride compounds used in the United States originates as a byproduct of phosphate rock mining in Florida.
Sodium Fluoride in Nature
In its natural form, sodium fluoride exists as villiaumite, a rare mineral first discovered on the Los Islands off the coast of Guinea by French explorer Maxime Villiaume. It has since been found in scattered locations around the world: the Kola Peninsula in Russia, Mont Saint-Hilaire in Quebec, Lake Magadi in Kenya, parts of Greenland and Namibia, Minas Gerais in Brazil, and a handful of sites in New Mexico and Colorado.
Despite villiaumite being uncommon, fluorine itself is far from rare. It ranks as the 13th most abundant element in Earth’s crust, locked inside various rocks and minerals. Phosphate rock is by far the most commercially important source, containing fluorine that gets released during industrial processing.
How It’s Made Industrially
Commercial sodium fluoride production is straightforward chemistry. Manufacturers combine hydrofluoric acid with either sodium carbonate (soda ash) or sodium hydroxide (lye). The resulting salt is then separated by centrifuge and dried into a white crystalline powder. This powder is odorless, non-corrosive, and has an extremely high melting point of 993 °C, which makes it useful across a wide range of applications.
The hydrofluoric acid used in this process often comes from fluorite (calcium fluoride) ore or from the phosphate fertilizer industry, which brings us to one of the more controversial aspects of sodium fluoride’s origin story.
The Phosphate Rock Connection
Florida’s phosphate mining industry is the single largest source of fluoride compounds used in American water systems. When phosphate rock is processed into fertilizer, the reaction releases highly toxic gases, including hydrogen fluoride and silicon tetrafluoride. For decades, these gases simply vented into the atmosphere, causing serious damage to nearby farms and ranches.
During the 1960s, pressure from farmers forced manufacturers to install pollution scrubbers that captured these gases and converted them into fluorosilicic acid, a hazardous but containable liquid. That liquid is now the primary fluoride compound added to municipal water supplies across the country. It’s transported in tanker trucks from Florida fertilizer factories to water treatment plants nationwide. Sodium fluoride is used occasionally as well, but fluorosilicic acid dominates the market because it’s cheaper and more readily available.
This origin has drawn criticism. The fluoride added to drinking water is a captured industrial byproduct, not a pharmaceutical-grade compound. It contains trace amounts of arsenic and lead, though at levels regulators consider safe. The fluoride in your toothpaste, by contrast, is pharmaceutical grade and held to tighter purity standards. Under USP (United States Pharmacopeia) guidelines, sodium fluoride tablets must contain between 90% and 110% of the labeled amount of the compound.
Where It Ends Up
Dental health is the most familiar use. In 1945, Grand Rapids, Michigan became the first city in the world to add fluoride to its drinking water, launching a public health practice that now reaches roughly 73% of Americans on community water systems. The EPA’s maximum contaminant level for fluoride in drinking water is 4.0 milligrams per liter, a standard first set in 1986 and most recently reviewed in 2024.
But sodium fluoride has a long history outside of dentistry. It has been used for over a century as a wood preservative in Europe and the United States, protecting railroad ties, utility poles, and other lumber from decay fungi and subterranean termites. The first multi-salt wood preservative, patented by Dr. Wolman in Germany, was 85% sodium fluoride. In Australia and the U.S., concentrated fluoride rods (98% sodium fluoride) are still inserted into utility poles as an internal treatment against rot.
Its physical properties make it useful in manufacturing as well. Because it doesn’t burn or corrode and can withstand extremely high temperatures, sodium fluoride works well in processes like hot pressing and extrusion. It also plays roles in glass etching, metallurgy, and as a flux in certain metal-processing operations.
Natural Mineral vs. Industrial Byproduct
The sodium fluoride in consumer products is almost never mined from villiaumite deposits. The mineral is simply too rare and too scattered to be commercially viable. Instead, virtually all sodium fluoride is synthesized, either through direct chemical reactions or derived from fluoride captured during phosphate fertilizer production. The chemical formula is identical regardless of the source, but the purity, processing, and trace contaminants differ depending on whether the end product is destined for a toothpaste tube or a water treatment plant.