Most of the baking soda sold worldwide comes from trona ore, a mineral that formed tens of millions of years ago at the bottom of ancient evaporating lakes. The largest known deposit sits beneath southwestern Wyoming, where miners extract the ore and refiners convert it into the pure sodium bicarbonate you buy in a bright orange box. A smaller share of global production is made synthetically from salt and limestone using a nineteenth-century chemical process. But baking soda’s story stretches much further back than any mine or factory, from prehistoric lake beds to ancient Egyptian embalming rituals and even to the carbonate chemistry happening inside your own body right now.
Natron and the Ancient World
Long before anyone called it baking soda, people used naturally occurring sodium bicarbonate blended with related sodium salts. The most famous early source was Egypt’s Wadi Natrun, a chain of low-lying lakes northwest of Cairo. Evaporation concentrated the lake water into crusty mineral deposits called natron, a mixture of sodium carbonate, sodium bicarbonate, and smaller amounts of chloride and sulfate salts. Ancient Egyptians prized natron for mummification: packing the mineral around and inside a body pulled water out rapidly enough to prevent decay.1PubMed. Raman spectroscopy of natron: shedding light on ancient Egyptian mummification Natron also found its way into early glassmaking, cleaning, and food preparation. The word itself gave us “natrium,” the Latin name for sodium, which is why the element’s symbol on the periodic table is Na rather than So.
What made Wadi Natrun special was its geology: groundwater rich in dissolved sodium percolated through volcanic sediments and collected in shallow basins where intense desert heat drove off the water. The carbonates left behind were simply scraped up. This basic process, alkaline water plus evaporation equals sodium carbonate minerals, is the same mechanism that created the vastly larger deposits people mine today.
How Geology Built the World’s Biggest Baking Soda Reserve
About 50 million years ago, during the Eocene epoch, a series of large inland lakes occupied what is now the Green River Basin spanning parts of Wyoming, Colorado, and Utah. The climate was warm and wet enough to sustain these lakes for millions of years, but dry enough in certain periods that they shrank and concentrated their dissolved minerals. Rivers and groundwater carried sodium, calcium, and dissolved carbon dioxide into the lakes. As the water evaporated, sodium carbonate and sodium bicarbonate crystallized on the lake floor, building up layer after layer of evaporite minerals.
Researchers have studied what made these particular lakes so rich in carbonates. One leading explanation is that unusually high atmospheric carbon dioxide during the Eocene accelerated the weathering of silicate rocks on the surrounding landscape, flooding the lakes with bicarbonate-rich runoff.2Earth-Science Reviews. The Green River salt mystery: What was the source of the hyperalkaline lake waters? Another possibility is that carbon dioxide migrated upward along faults from deep in the earth’s crust, dissolving into the lake water from below. Either way, these conditions produced the largest sodium carbonate evaporite deposits in the geologic record. The mineral that dominates the Wyoming deposit is trona, a hydrated combination of sodium carbonate and sodium bicarbonate. Colorado’s Piceance Creek Basin holds a related mineral called nahcolite, which is essentially pure crystalline sodium bicarbonate.
The deposition was not a one-time event. Detailed studies of the Wilkins Peak Member, one of the key geological layers in the Green River Formation, show repeating patterns of evaporite minerals. These recurring cycles were driven by fluctuations in how much water flowed into the lake, how fast it evaporated, and seasonal temperature swings, much like what researchers observe in modern hypersaline lakes today.3Geosites. Recurring lacustrine depositional successions in the Wilkins Peak Member, Green River Formation The result was an enormous underground layer cake of trona beds, some of them more than three meters thick, buried several hundred meters below the surface of southwestern Wyoming.
From Underground Ore to Kitchen Staple
Wyoming’s trona is mined using two main methods. Conventional underground mining sends workers and machines into shafts hundreds of meters deep to cut out the trona beds mechanically. Solution mining, the other approach, pumps hot water down into the deposit to dissolve the trona, then brings the mineral-laden brine back to the surface. Either way, the raw trona still needs refining before it becomes the familiar white powder.
The basic refining steps are straightforward. Crushed trona ore is dissolved in hot water, which separates the soluble sodium carbonates from insoluble impurities like shale. The solution is filtered, then carbon dioxide gas is bubbled through it at a controlled temperature. That CO₂ reacts with the dissolved sodium carbonate and converts it into sodium bicarbonate, which is less soluble and precipitates out as crystals.4TMP Universal Journal of Advances in Pharmaceutical Sciences. Trona-Based Green Synthesis and Analysis of Sodium Bicarbonate: An Eco – Friendly Approach The crystals are collected, washed, and dried. What you get is food-grade sodium bicarbonate, pure enough to leaven bread, brush teeth, or neutralize a sour stomach.
The United States is the world’s dominant producer of natural soda ash and sodium bicarbonate, and virtually all of it comes from Wyoming’s Green River deposits. Turkey and a handful of other countries also mine natural trona, but Wyoming’s reserves dwarf all others combined. The ore body is so large that at current extraction rates it could last centuries.
The Synthetic Route and the Solvay Process
Not all baking soda starts as trona. In regions without natural deposits, sodium bicarbonate is manufactured synthetically using variations of the Solvay process, a method invented in Belgium in the 1860s. The classic version starts with two cheap raw materials: salt (sodium chloride) and limestone (calcium carbonate). Limestone is heated in a kiln to produce carbon dioxide gas and quicklime. Meanwhile, ammonia is dissolved in a concentrated salt brine. When that CO₂ is bubbled through the ammoniated brine, sodium bicarbonate precipitates out. The ammonia is then recovered by treating the leftover ammonium chloride solution with the quicklime, which regenerates the ammonia for reuse.5Journal of Cleaner Production. Cleaner production in the Solvay Process: general strategies and recent developments
If the goal is soda ash (sodium carbonate, used in glass and detergents), the sodium bicarbonate produced in the Solvay process is heated further so it decomposes into sodium carbonate, water, and carbon dioxide. But if the end product is baking soda itself, that extra heating step is skipped and the sodium bicarbonate is simply dried and packaged. In either case, the process is elegantly circular: ammonia and much of the CO₂ are recycled within the plant. The main waste product is calcium chloride, which has limited commercial value and creates a disposal challenge.
Solvay plants operate across Europe, Asia, and parts of Africa and South America. In the United States, the abundance of cheap natural trona largely displaced synthetic production decades ago, making Solvay-derived baking soda relatively uncommon in North American markets. Globally, though, a significant fraction of sodium bicarbonate still comes from synthetic routes, especially in countries far from natural trona deposits.
The Environmental Side of Making Baking Soda
Mining trona and refining it consumes energy, but the carbon footprint is generally lower than the synthetic alternative. The Solvay process requires burning limestone in kilns, which releases CO₂ both from the fuel and from the limestone itself. Estimates suggest that roughly 0.2 to 0.4 tons of CO₂ are emitted for every ton of soda ash produced via the classic Solvay method.6Results in Engineering. Toward sustainable soda ash production: A critical review on eco-impacts, modifications, and innovative approaches Modified versions of the process aim to cut that figure by eliminating the limestone calcination step or by integrating CO₂ captured from industrial exhaust streams. Some researchers have explored using steelmaking slag as a mineral source for these modified reactions, essentially turning an industrial waste product into a feedstock for baking soda production while simultaneously sequestering carbon dioxide.
Natural trona refining has its own environmental considerations, including the energy needed to mine, dissolve, and recrystallize the ore, and the water consumed in solution mining. But because the trona already contains the carbonate chemistry you need, there is no limestone kiln and far less chemical processing. That gives natural production a meaningful advantage in carbon intensity, which is one reason the Wyoming operations have remained competitive against synthetic plants worldwide.
Volcanic Carbonates and Unusual Natural Sources
Trona deposits and soda lakes are not the only places nature produces sodium carbonates. In northern Tanzania, the volcano Ol Doinyo Lengai erupts a truly bizarre lava unlike anything else on the planet. Instead of the usual silicate-rich molten rock, its lava is dominated by sodium and potassium carbonate minerals. The erupted material is so rich in sodium carbonate that it dissolves in rainwater within weeks, something no other volcanic rock does. The runoff feeds into nearby Lake Natron, which, like its Egyptian namesake, is a highly alkaline soda lake ringed with natron deposits.
This volcanic link illustrates that sodium carbonates are not exclusively the product of evaporating lake water. Deep earth processes can concentrate carbon and sodium in magmas and hydrothermal fluids, bringing carbonate chemistry to the surface through eruptions and fault-line seeps. Some researchers studying the Green River Formation’s alkalinity have pointed to similar deep CO₂ migration as a possible contributor to the ancient lakes’ extreme chemistry.2Earth-Science Reviews. The Green River salt mystery: What was the source of the hyperalkaline lake waters?
Bicarbonate Inside Your Own Body
You do not need to open a box to encounter sodium bicarbonate. Your body manufactures it continuously. The bicarbonate buffering system is one of the primary ways your blood maintains its tightly regulated pH. Your kidneys play a central role, reclaiming bicarbonate from filtered blood and adjusting how much gets reabsorbed depending on whether conditions are trending acidic or alkaline. Research has shown that even a small shift of 0.1 pH units in blood plasma changes bicarbonate reabsorption by about ten percent, a sensitive feedback loop that keeps blood chemistry remarkably stable.7PubMed. Filtered bicarbonate and plasma pH as determinants of renal bicarbonate reabsorption
Your pancreas is another prolific bicarbonate factory. When partially digested food leaves the stomach, it is drenched in hydrochloric acid. The pancreas responds by secreting a fluid rich in bicarbonate into the upper small intestine, neutralizing that acid so digestive enzymes can work and intestinal tissue is not damaged. Generating such high concentrations of bicarbonate requires active pumping against a gradient, and researchers have identified multiple proton pumps in pancreatic duct cells that drive this process.8PubMed Central. Pancreatic bicarbonate secretion involves two proton pumps When you swallow an antacid tablet made of sodium bicarbonate, you are essentially supplementing a system your body already runs on its own.
Bicarbonate in Ruminant Digestion
Humans are not the only animals that depend on bicarbonate for gut chemistry. Cows, sheep, and other ruminants produce enormous quantities of bicarbonate-rich saliva, sometimes exceeding 100 liters a day in dairy cattle. This saliva flows into the rumen, the large fermentation chamber where microbes break down plant fiber, and acts as a natural buffer against the acids those microbes produce. Research on dairy cows has shown that for every additional mole of bicarbonate delivered to the rumen via saliva, ruminal pH rises by about 0.06 units, a meaningful shift in an environment where even small pH drops can suppress fiber digestion and cause health problems.9PubMed. Dynamic changes in salivation, salivary composition, and rumen fermentation associated with duration of high-grain feeding in cows
Dairy farmers have long recognized this connection. When cows are fed high-grain diets that push rumen acidity up, a common intervention is adding sodium bicarbonate directly to the feed as a buffer supplement. It is the same compound you bake muffins with, just repackaged for a very different digestive system. The practice underscores how universal bicarbonate’s acid-neutralizing chemistry is across the animal kingdom.
Industrial Uses That Have Nothing to Do With Baking
The name “baking soda” undersells the compound’s range. One of its most impactful industrial applications is scrubbing sulfur dioxide out of power-plant exhaust. When sodium bicarbonate, trona, or nahcolite is injected as a dry powder into a flue gas stream, it reacts with SO₂ and can remove up to 95 percent of the pollutant under the right conditions.10ACS Publications. Control of SO2 Emissions by Dry Sorbent Injection This dry sorbent injection method is simpler and less water-intensive than wet scrubbing systems, which made it attractive for retrofitting older coal-fired boilers that lacked space for large wet-scrubber installations.
Beyond emissions control, sodium bicarbonate is used in fire extinguishers (the classic “BC” dry chemical type), water treatment, animal feed, pharmaceutical formulations, and even as a mild abrasive in sandblasting for delicate restoration work on historic buildings. Its appeal in all these roles comes down to the same property: it reacts with acids, decomposes cleanly when heated, and leaves behind only benign residues. A compound that formed at the bottom of Eocene lakes ends up doing heavy lifting in contexts its ancient origins could never have predicted.
Why Trona Dominates Over Synthetic Production in the U.S.
For most of the twentieth century, the Solvay process was the primary way the world made sodium carbonate and bicarbonate. That changed as Wyoming’s trona reserves were developed at industrial scale starting in the 1940s and 1950s. The economics are hard to argue with: the mineral is already there, already containing the sodium and carbonate that a Solvay plant has to assemble from scratch using salt, limestone, and ammonia. Natural trona refining requires fewer chemical steps, generates less waste, and avoids the energy-intensive limestone calcination that drives much of the Solvay process’s carbon footprint.6Results in Engineering. Toward sustainable soda ash production: A critical review on eco-impacts, modifications, and innovative approaches
By the early 2000s, every Solvay soda ash plant in the United States had closed, unable to compete with mined trona on cost. The shift was so complete that the country went from being a major synthetic producer to being almost entirely dependent on natural deposits. Other countries without accessible trona, particularly in Europe and Asia, continue to rely on the Solvay process and its modern variants, but the global trend has tilted toward natural sourcing wherever geology permits. China and Turkey have both expanded natural trona operations in recent decades, following the American model.
The practical upshot for anyone buying baking soda in the United States is that the white powder in the box almost certainly traces its origin to a 50-million-year-old lake bed in Wyoming. It was dissolved out of the ground, purified, recrystallized, and shipped to a grocery store shelf. The chemistry that makes it useful for leavening bread, settling a sour stomach, or scrubbing a pan is the same chemistry that deposited it underground in the first place: a simple reaction between sodium, carbon dioxide, and water, playing out on a planetary scale and then scaled back down to fit in your pantry.