Brimstone, the ancient name for elemental sulfur, has been used for everything from purging evil spirits to manufacturing the world’s most-produced industrial acid. The word itself comes from the Old English “brynstān,” meaning “burning stone,” a nod to the pale yellow mineral’s tendency to catch fire with a choking, acrid smoke. That dual identity, part spiritual terror and part chemical workhorse, has followed sulfur through thousands of years of human history and into a future that includes next-generation batteries and deep-sea biology.
The Symbolic Weight of Brimstone
Long before anyone understood sulfur’s chemistry, people associated it with divine punishment. The Hebrew Bible describes the destruction of Sodom and Gomorrah with “fire and brimstone” raining from the sky. The Book of Revelation places brimstone in a lake of eternal torment. Similar imagery appears in the Quran and in various Greek and Roman texts, where volcanic landscapes belching sulfurous fumes were linked to the underworld and the wrath of the gods. The connection was intuitive: sulfur burns with an eerie blue flame, releases suffocating gas, and is found around volcanoes and hot springs, places that already looked like gateways to something infernal.
This symbolic baggage gave brimstone a long career in folk medicine and ritual purification. Ancient Greeks burned sulfur to fumigate homes after illness, and Roman farmers used it against crop pests. The logic was partly spiritual, a burning that “cleansed” corruption, and partly practical, since sulfur dioxide really does kill insects and mold. Over time, the spiritual associations faded for most practical users, but the word “brimstone” retains its fire-and-damnation flavor in English to this day.
What Sulfur Actually Is and Where It Comes From
Sulfur is an element, number 16 on the periodic table, and it is one of the most common substances on Earth and across the solar system. It exists in multiple chemical states, which is part of why it shows up in so many different contexts, from the deep ocean floor to the upper atmosphere. Sulfur plays roles in everything from the formation of Earth’s core to the composition of volcanic gas, and its chemistry is used by geoscientists to trace the evolution of the planet’s atmosphere and oceans over billions of years.1Elements. Sulfur: A Ubiquitous and Useful Tracer in Earth and Planetary Sciences
Historically, sulfur was mined from volcanic deposits in places like Sicily, Japan, and Indonesia, often by hand in brutal conditions. Today, most of the world’s sulfur supply comes not from mines but from oil and gas refining. Petroleum and natural gas contain sulfur compounds that must be stripped out before the fuels can be sold, and the recovered sulfur is then funneled into industrial use. This means sulfur production is closely tied to fossil fuel output, and there is generally a surplus rather than a shortage.
Sulfuric Acid and the Backbone of Industry
The single biggest use of sulfur worldwide is the production of sulfuric acid. It is sometimes called the most important industrial chemical on the planet, and global production exceeds 250 million tonnes per year. The largest consumer of sulfuric acid, by far, is the fertilizer industry. Phosphate rock, the raw material for phosphorus fertilizers, is essentially useless until it is dissolved in sulfuric acid to produce phosphoric acid and then the fertilizers that feed billions of people. Without sulfur, modern agriculture at its current scale would not function.
Beyond fertilizer, sulfuric acid is used in metal ore processing, petroleum refining, chemical manufacturing, and wastewater treatment. It is the starting reagent or intermediate in an enormous range of industrial processes. When economists want a quick-and-dirty indicator of a country’s industrial output, sulfuric acid production is sometimes cited as a proxy, which says something about how deeply embedded sulfur is in the global economy.
Sulfur in Agriculture Beyond Fertilizer
Sulfur has a direct agricultural role that goes beyond being a raw ingredient for acid. It is an essential plant nutrient, required for the production of certain amino acids and enzymes, and many soils around the world are sulfur-deficient. Farmers apply elemental sulfur to fields both as a nutrient source and as a soil amendment. When elemental sulfur is added to soil, bacteria oxidize it into sulfuric acid, which lowers the soil pH. That acidification effect can be useful in alkaline soils where crops struggle to take up iron and other nutrients. Research in southern Brazil found that applying roughly 50 kilograms per hectare of elemental sulfur to the top 20 centimeters of soil lowered the pH by about one unit, a meaningful shift for many crops.2Revista Brasileira de Engenharia Agrícola e Ambiental. Elemental sulfur recommendation for pH reduction in soils from Southern Brazil
However, this microbial conversion also affects the soil biology itself. Repeated sulfur fertilization can change microbial biomass and enzyme activity in the soil, which means the amendment is not entirely benign and needs to be managed carefully.3Canadian Journal of Soil Science. Impact of Elemental Sulfur Fertilization on Agricultural Soils. I. Effects on Microbial Biomass and Enzyme Activities
Sulfur also works as a fungicide. Dusting or spraying crops with sulfur to control fungal diseases is one of the oldest pest-management strategies in agriculture, predating modern chemistry by centuries. Field trials on spring wheat showed that foliar sulfur application reduced powdery mildew on upper leaves and ears. When combined with a commercial fungicide, sulfur was more effective at controlling mildew than either treatment alone, suggesting it still has a practical place even alongside modern agrochemicals.4Annals of Applied Biology. The effect of applied sulphur on the growth, grain yield and control of powdery mildew in spring wheat
Rubber Vulcanization and Materials Science
One of sulfur’s most transformative industrial roles arrived in the nineteenth century with the discovery of vulcanization. Raw natural rubber is sticky in heat and brittle in cold, which limits its usefulness. When sulfur is heated with rubber, it creates cross-links between the polymer chains, turning the material into something flexible, durable, and resilient across a wide temperature range. Every car tire, garden hose, and rubber gasket relies on this sulfur-driven cross-linking process.
The principle extends to newer materials as well. Researchers have applied sulfur vulcanization to bioplastics called polyhydroxyalkanoates, which are biodegradable polymers produced by bacteria. By cross-linking these bioplastics with sulfur, scientists can tune their physical properties, making them tougher and more resistant to solvents, while potentially preserving their biodegradability.5PubMed Central. Sulfur Vulcanization and Material Properties of Polyhydroxyalkanoates with Unsaturated Side Chain
Sulfur also shows up in road construction. Sulfur-extended asphalt, where elemental sulfur is blended with asphalt binder at ratios up to 50/50, has been explored as a way to stretch expensive asphalt supplies and improve pavement performance. In these mixes, the sulfur acts partly as an extender and partly as a filler or stabilizer.6Cleaner Waste Systems. Effects of sulfur by-products on the durability and sustainability of asphalt pavement construction: A systematic review
Pharmaceuticals Built on Sulfur
Sulfur sits quietly at the heart of a staggering number of medications. Sulfur-containing groups appear in antibiotics, blood pressure drugs, diabetes medications, cancer treatments, and anti-inflammatory agents. One review identified 362 FDA-approved drugs containing sulfur, making it the most common heteroatom in pharmaceuticals after oxygen and nitrogen. The most familiar sulfur-based drug classes include sulfonamide antibiotics, penicillins, and sulfone compounds.7PubMed Central. Sulfur Containing Scaffolds in Drugs: Synthesis and Application in Medicinal Chemistry
Sulfonamides in particular have had a remarkable trajectory. They were among the first synthetic antimicrobial drugs, introduced in the 1930s, and they changed medicine by proving that chemical compounds could fight bacterial infections. Today sulfonamides have expanded well beyond antibiotics into roles as diuretics, treatments for glaucoma, and inhibitors of enzymes involved in cancer and inflammation.8ChemistrySelect. Sulfonamides: Historical Perspectives, Therapeutic Insights, Applications, Challenges, and Synthetic Strategies More than 150 FDA-approved drugs rely specifically on sulfonyl or sulfonamide scaffolds, covering an enormous therapeutic range.9PubMed Central. Pharmaceutical and medicinal significance of sulfur (SVI)-Containing motifs for drug discovery: A critical review
Food Preservation With Sulfur Dioxide
Sulfur dioxide, a gas produced when sulfur burns, has been used as a food preservative for centuries. Wine producers have added sulfites since at least the Roman era to prevent spoilage and oxidation. Today sulfur dioxide and its sulfite salts are used in dried fruits, wine, juice, and a variety of processed foods to prevent browning, inhibit microbial growth, and extend shelf life.10PubMed. The chemistry and technology of the pretreatment and preservation of fruit and vegetable products with sulfur dioxide and sulfites
The trade-off, however, is that sulfite residues in food can trigger allergic-type reactions in sensitive individuals, particularly some people with asthma. Regulators around the world set limits on sulfite levels in food and require labeling, but balancing effective preservation with residue safety remains a challenge for the food industry.11PubMed Central. Sulfur Dioxide in Food: A Review of Its Preservative Mechanisms, Safety Concerns, and the Rise of Smart Detection Systems If you have ever noticed “contains sulfites” on a wine bottle, that is the regulatory result of decades of balancing these concerns.
Paper and Pulp Manufacturing
The global paper industry depends on sulfur in a less visible but enormous way. The dominant method for turning wood into pulp is the kraft process, which uses sulfur-containing chemicals to dissolve the lignin that binds wood fibers together. Kraft pulping accounts for the majority of the world’s pulp production, but the process generates sulfurous byproducts that have historically been a significant source of pollution and the unpleasant smell associated with paper mills.12PubMed Central. Is Kraft Pulping the Future of Biorefineries? A Perspective on the Sustainability of Lignocellulosic Product Development
The sulfur chemistry here is complex. Wood chips in the kraft process adsorb hydrogen sulfide and methyl mercaptan from the cooking liquor, generating organic sulfur compounds responsible for the characteristic odor.13PubMed. Quantification and reduction of organic sulfur compound formation in a commercial wood pulping process The lignin left over, called kraft lignin, is itself a sulfur-containing byproduct. Researchers have been working on desulfurizing kraft lignin to make it useful as a chemical feedstock rather than just burning it for energy.14Wood Science and Technology. Desulfurization of kraft lignin The paper industry’s sulfur story, in other words, is as much about managing a problematic byproduct as it is about using sulfur as a tool.
Energy Storage and Environmental Recovery
Sulfur is gaining attention in energy technology for a reason that would have baffled its ancient users: batteries. Lithium-sulfur batteries are a promising alternative to conventional lithium-ion cells because their theoretical energy density reaches up to 2,600 watt-hours per kilogram, roughly five times higher than today’s standard lithium-ion batteries.15Materials Science and Engineering: R: Reports. A review of lithium–sulfur batteries at different working conditions: The role of ambient temperature, external force, and electromagnetic field Sulfur is also cheap and abundant, which makes the technology attractive for electric vehicles and grid-scale storage. The catch is that lithium-sulfur batteries still face practical challenges around cycle life and performance under varying conditions, so they have not yet displaced lithium-ion in commercial products. But they are one of the most actively researched battery technologies in the world.
On the environmental side, sulfur recovery from industrial flue gas is a growing field. Coal-fired power plants release sulfur dioxide as a pollutant, and technologies now exist to capture that SO2 and convert it back into elemental sulfur, turning a waste stream into a marketable product.16Process Safety and Environmental Protection. Economic performance assessment of elemental sulfur recovery with carbonate melt desulfurization process This kind of circular approach is becoming more economically viable as sulfur demand remains high and environmental regulations tighten.
The Smell That Saves Lives
Natural gas is odorless. This is a problem, because a gas leak in a home can cause an explosion before anyone realizes something is wrong. The solution, implemented in the early twentieth century after a devastating school explosion in Texas, was to add tiny amounts of foul-smelling sulfur compounds to the gas supply. These organosulfur odorants, such as tert-butyl mercaptan and methyl ethyl sulfide, are deliberately injected into gas lines so that even a small leak produces a distinctive rotten-egg smell that humans detect at extremely low concentrations.17PubMed Central. Natural gas odorants: A scoping review of health effects
Getting the dose right matters. Too little odorant and people might not notice a leak; too much can cause nuisance complaints and even health concerns for sensitive individuals. Gas utilities continuously monitor odorant levels in the distribution system, and sensor technology has advanced to allow selective detection of individual sulfur compounds in the gas stream.18PubMed. Selective monitoring of natural gas sulphur-based odorant mixture of t-butyl mercaptan and methyl ethyl sulphide using an array of microfluidic gas sensors It is a small, unglamorous use of sulfur chemistry, but it prevents an unknowable number of explosions and deaths every year.
Sulfur-Powered Life in the Deep Ocean
Perhaps the most unexpected chapter in sulfur’s story has nothing to do with human industry at all. At hydrothermal vents on the ocean floor, entire ecosystems run on sulfur instead of sunlight. Bacteria living in and around these vents oxidize hydrogen sulfide and other sulfur compounds for energy, using that energy to build organic molecules from carbon dioxide in a process called chemosynthesis. Animals like giant tube worms and clams thrive at these vents because they host these sulfur-oxidizing bacteria as internal symbionts, essentially farming them for food.19PubMed. Chemosynthetic symbioses
This sulfur-based metabolism is not limited to the vents themselves. Sulfur-oxidizing bacteria from the SUP05 group are found widely across deep-ocean environments and appear to also use hydrogen as an energy source alongside sulfur, contributing to primary production throughout the deep sea in ways that were not appreciated until metagenomic studies revealed the extent of their activity.20PubMed Central. Evidence for hydrogen oxidation and metabolic plasticity in widespread deep-sea sulfur-oxidizing bacteria The discovery of these ecosystems in the late 1970s reshaped how biologists think about the requirements for life and opened serious conversations in astrobiology about whether sulfur-driven life could exist on other worlds, such as Jupiter’s moon Europa, where liquid water and chemical energy might coexist far from any star.