Manganese turns up in an extraordinary range of natural settings, from the interiors of exploding stars to the surface of Mars, from ocean-floor nodules growing a few millimeters per million years to the soils in your backyard. It is the twelfth most abundant element in Earth’s crust, and more than 30 distinct manganese oxide minerals have been identified across geological environments worldwide. What makes manganese unusual is not just how common it is, but how actively it cycles through rock, water, sediment, and living organisms, driven largely by changes in oxygen levels and the metabolism of microbes.
Forged in Stellar Explosions
Every atom of manganese on Earth was created inside a star before our solar system existed. Most of it traces back to a specific kind of stellar death: the thermonuclear explosion of a white dwarf, known as a Type Ia supernova. These explosions produce manganese alongside iron, and the ratio between the two elements depends on the mass of the white dwarf that detonated. Models involving white dwarfs near a critical mass threshold produce manganese-to-iron ratios that are distinctly high compared to other explosion types.1Astronomy & Astrophysics. Solar abundance of manganese: a case for near Chandrasekhar-mass Type Ia supernova progenitors More recent modeling work has shown that other explosion scenarios, particularly those involving helium detonations on lighter white dwarfs, can also contribute meaningfully to manganese production.2Astronomy & Astrophysics. Nucleosynthesis imprints from different Type Ia supernova explosion scenarios and implications for galactic chemical evolution In other words, manganese has multiple stellar recipes, but explosive thermonuclear burning in dense stellar remnants is the dominant kitchen.
After being scattered into interstellar space by these explosions, manganese atoms were swept up into the cloud of gas and dust that collapsed to form our sun and planets roughly 4.6 billion years ago. From there, chemistry took over from astrophysics.
In Earth’s Crust and Continental Ore Deposits
Manganese makes up about 0.1% of Earth’s crust by weight, which sounds small but translates into vast quantities spread through hundreds of rock types. It does not usually appear as a free metal. Instead, it combines with oxygen, carbon, and other elements to form minerals like pyrolusite, rhodochrosite, and hausmannite. More than 30 manganese oxide minerals alone have been catalogued, and they show up in geological settings ranging from ancient marine sediments to modern desert surfaces.3PubMed Central. Manganese oxide minerals: crystal structures and economic and environmental significance
The largest concentrated deposits of manganese ore on land formed during specific windows in Earth’s history, often tied to dramatic geological and climatic upheavals. Continental breakups, glaciations, and even mass extinction events created conditions that concentrated manganese into economically mineable layers. These ores accumulated through a mix of hydrothermal activity on the seafloor and chemical processes within marine sediments, often in association with carbon-rich shales.4Isotope Geochemistry. The Major Epochs and Phases of Manganese Accumulation in the Earth’s History Many of the world’s biggest manganese deposits, including those in South Africa’s Kalahari Basin and similar formations elsewhere, started as sediments on shallow continental shelves during the early Proterozoic era, roughly two billion years ago.5Economic Geology. The major early Proterozoic sedimentary iron and manganese deposits and their tectonic setting
South Africa alone holds an estimated three-quarters of the world’s known manganese ore reserves. Other major deposits exist in Australia, Gabon, Brazil, India, China, and Ukraine. Nearly all commercial manganese is mined from these ancient sedimentary formations, then used overwhelmingly in steelmaking, where it strengthens the alloy and removes sulfur and oxygen during smelting.
Covering the Ocean Floor
Some of the most striking concentrations of manganese in nature sit on the deep ocean bottom, where potato-sized lumps called polymetallic or manganese nodules carpet huge stretches of the abyssal plains. These nodules form when dissolved manganese and iron in seawater oxidize into tiny solid particles that slowly precipitate onto a nucleus, which might be a shark tooth, a fragment of volcanic rock, or a bit of shell. The growth rate is almost unimaginably slow. Nodules formed by this process, called hydrogenetic precipitation, add just a few millimeters of material over a million years.6Ore Geology Reviews. Oxic bottom water dominates polymetallic nodule formation around the Caiwei Guyot, northwestern Pacific Ocean
During this glacially slow growth, the nodules scavenge other metals from seawater with remarkable efficiency. The manganese oxide surfaces can concentrate elements like cobalt, platinum, and cerium by factors of up to a billion relative to their abundance in the surrounding water.6Ore Geology Reviews. Oxic bottom water dominates polymetallic nodule formation around the Caiwei Guyot, northwestern Pacific Ocean This is why these nodules have attracted intense commercial interest: they contain not just manganese but also nickel, copper, and cobalt, metals critical for batteries and electronics. The Clarion-Clipperton Zone in the central Pacific, an area roughly the size of the contiguous United States, is particularly rich in these formations.
A related phenomenon occurs on the flanks and summits of underwater mountains, or seamounts, where ferromanganese crusts build up as thin mineral coatings on exposed rock. The composition of these crusts varies with water depth and the rate at which carbonate from plankton dissolves.7Earth and Planetary Science Letters. The influence of the carbonate dissolution rate on the growth and composition of Co-rich ferromanganese crusts from Central Pacific seamount areas Unlike nodules resting on soft sediment, crusts are bonded to hard substrates and tend to be enriched in cobalt, making them another target for potential deep-sea mining.
Nodules also form in freshwater lakes, though these have been less studied commercially. The manganese oxide minerals found in both ocean nodules and lake sediments are described as ubiquitous in soils and sediments globally, participating in chemical reactions that shape groundwater composition.3PubMed Central. Manganese oxide minerals: crystal structures and economic and environmental significance
Dissolved in Rivers, Lakes, and Open Ocean
Manganese does not just sit locked in minerals. It constantly cycles between solid and dissolved forms in water, driven mainly by how much oxygen is available. In oxygen-rich water, manganese tends to be in its oxidized, insoluble form, settling out as particles. When oxygen drops, manganese dissolves back into the water as a reduced, soluble ion. This redox cycling gives manganese a dynamic presence in nearly every aquatic environment.
In lakes that develop seasonal layering, the pattern is especially clear. During summer, many temperate lakes stratify: warm surface water sits on top of cold, stagnant bottom water. As organic matter sinks and decomposes, the bottom water loses its oxygen. Once conditions turn anoxic, manganese locked in the sediment dissolves and accumulates in the deep water. One well-studied English lake showed dissolved manganese climbing to around 50 micromolar in the oxygen-depleted bottom layer during summer.8Water Research. A study of the cycling of manganese and other elements in a seasonally anoxic lake, Rostherne Mere, U.K. When the lake mixes in autumn and oxygen reaches the deep water again, the manganese re-oxidizes and sinks back to the sediment. Measurements using sediment traps have shown that less than 10% of the manganese reaching the sediment in winter is permanently buried; most is rapidly reduced and released back into the water, completing its cycle.9Limnology and Oceanography. The dynamics of iron and manganese in a seasonally anoxic lake; direct measurement of fluxes using sediment traps
In the open ocean, dissolved manganese concentrations are typically very low away from sources. Measurements in the Southern Ocean between Tasmania and Antarctica found dissolved manganese below about 0.3 nanomoles per liter through most of the transect, with localized bumps near the Antarctic continental slope where sediments and hydrothermal inputs added extra manganese.10Limnology and Oceanography. Manganese biogeochemistry in the Southern Ocean, from Tasmania to Antarctica Phytoplankton take up dissolved manganese as a micronutrient, further drawing down surface concentrations. In the Southern Ocean, the ratio of manganese to phosphorus inside diatom cells suggested the organisms were under iron stress, hinting at how the cycles of different trace metals intertwine in remote waters.10Limnology and Oceanography. Manganese biogeochemistry in the Southern Ocean, from Tasmania to Antarctica
The Black Sea offers perhaps the most dramatic example of manganese’s redox behavior in a large body of water. It has a permanently anoxic deep layer rich in hydrogen sulfide. Manganese cycles through a distinct “suboxic” zone, 15 to 50 meters thick, sandwiched between the oxygenated surface and the sulfidic depths. In this zone, manganese shifts back and forth between dissolved and particulate forms along surfaces of equal water density that deepen toward the Turkish coast.11Deep Sea Research Part A. Oceanographic Research Papers. The biogeochemistry of manganese and iron in the Black Sea
In Soils, Where Plants Need It
Manganese is an essential micronutrient for plants, required for photosynthesis and several enzyme systems. Its availability in soil depends heavily on acidity and oxygen levels. In acidic, waterlogged soils, manganese becomes highly soluble, sometimes to the point of toxicity for crops. Research has shown that at a soil pH of 5, nearly all of the manganese converts to water-soluble and exchangeable forms even at relatively high oxygen levels. Between pH 6 and 8, the same conversion requires much lower oxygen conditions.12Soil Science Society of America Journal. Transformation of Manganese in a Waterlogged Soil as Affected by Redox Potential and pH Farmers dealing with acidic, poorly drained fields often encounter manganese toxicity in their crops, while those on alkaline, well-aerated soils sometimes see manganese deficiency. Liming acidic soils to raise the pH is one of the simplest interventions to bring manganese availability back into a healthy range.
Manganese’s role in photosynthesis is ancient and fundamental. In plants, the oxygen-evolving complex of photosystem II contains a cluster of four manganese atoms that split water molecules, releasing the oxygen we breathe. Recent experiments have demonstrated that modern photosystem II can oxidize dissolved manganese ions and form manganese oxide particles when illuminated, supporting the idea that the earliest forms of photosynthesis used manganese oxidation as a stepping stone before evolving full water-splitting capability.13Nature Communications. Light-driven formation of manganese oxide by today’s photosystem II supports evolutionarily ancient manganese-oxidizing photosynthesis
The Microbial Engine Behind Manganese Cycling
Bacteria and fungi are arguably the most important agents moving manganese through the environment. The manganese oxide minerals produced by microbial activity are considered the most abundant and highly reactive manganese oxide phases on Earth’s surface.14Annual Review of Earth and Planetary Sciences. BIOGENIC MANGANESE OXIDES: Properties and Mechanisms of Formation These biogenic oxides have much higher surface areas and chemical reactivity than their purely geological counterparts, making them powerful scavengers of heavy metals and organic contaminants in soils and groundwater.
The bacteria responsible for oxidizing manganese are spread across many evolutionary lineages, but they share a common biochemical tool: an enzyme related to the multicopper oxidase family that strips electrons from dissolved manganese, converting it from its soluble reduced form to insoluble manganese oxide particles.14Annual Review of Earth and Planetary Sciences. BIOGENIC MANGANESE OXIDES: Properties and Mechanisms of Formation Fungi and other microorganisms also participate, precipitating manganese into biogenic minerals including low-crystallinity birnessite and manganese oxalates.15PubMed Central. Involvement of Bacterial and Fungal Extracellular Products in Transformation of Manganese-Bearing Minerals and Its Environmental Impact
On the flip side, other microbes use manganese oxides as an electron acceptor in anaerobic respiration, essentially “breathing” manganese the way we breathe oxygen. Bacteria like Geobacter and Shewanella species can couple the breakdown of organic carbon to the reduction of solid manganese oxide, dissolving it back into the water. This is not a trivial trick: manganese oxide turns out to be an efficient electron acceptor, comparable in energy yield to nitrate and capable of outcompeting sulfate reduction and methane production in sediments where all these processes vie for dominance.16PubMed. Iron and manganese in anaerobic respiration: environmental significance, physiology, and regulation Because manganese oxides are solids rather than dissolved molecules, these bacteria have had to evolve special machinery to extend their respiratory chain to the cell surface, shuttling electrons outward to reach the mineral.17PubMed Central. Dissimilatory reduction of extracellular electron acceptors in anaerobic respiration
This microbial tug-of-war between oxidizers and reducers keeps manganese moving through soils, sediments, and water columns worldwide. It is one of the reasons manganese does not simply accumulate in one place and stay there.
Hydrothermal Vents and Desert Varnish
Two of the more exotic places manganese concentrates in nature are deep-sea hydrothermal vents and the sun-baked surfaces of desert rocks. At hydrothermal vents, superheated water laden with dissolved metals pours out of cracks in the ocean floor. These vents are a major source of dissolved manganese to the oceans, with concentrations reaching around 5 millimolar in the hottest smokers and gradually dropping as the plume disperses and the manganese oxidizes.18Geochimica et Cosmochimica Acta. Manganese scavenging and oxidation at hydrothermal vents and in vent plumes Manganese-oxidizing bacteria thrive in the warm, metal-rich water around these vents, accelerating the conversion of dissolved manganese into solid oxide particles that settle out over wide areas of the seafloor.
In deserts, a thin, dark coating called rock varnish builds up on exposed stone surfaces over thousands of years. This coating is rich in manganese and iron oxides mixed with clay. Its formation is largely biological: communities of cyanobacteria, fungi, and other microbes living on and inside the rock surface concentrate manganese from dust and rain, producing a dark, protective mineral layer. Rock varnish forms most readily where microbial weathering of the underlying stone proceeds extremely slowly, allowing the coating to build up rather than being outpaced by erosion.19Springer Link / Oecologia. Biogenic rock varnishes of the negev desert (Israel) an ecological study of iron and manganese transformation by cyanobacteria and fungi Rock varnish has attracted attention beyond geology: because its chemistry reflects environmental conditions at the time each layer formed, researchers have tried to use it as an archive of past climate. It also features in debates about interpreting dark coatings found on Martian rocks.
Manganese on Mars
Mars hosts manganese in forms that have raised intriguing questions about the planet’s past. Analysis of Martian meteorites, specifically the paired samples known as Northwest Africa 7034 and 7533, revealed manganese-rich regions containing up to 34% manganese by weight. The dominant manganese minerals in these regions are hollandite-structured oxides, with most of the manganese in the highly oxidized 4+ state.20Elsevier. Manganese oxides in Martian meteorites Northwest Africa (NWA) 7034 and 7533 On Earth, generating and preserving manganese in this oxidized state almost always requires the presence of free oxygen, at least in significant sedimentary deposits. The Curiosity and Perseverance rovers have also detected manganese oxide coatings on rocks in Gale Crater and Jezero Crater. Whether these Martian manganese oxides formed through oxidizing fluids, ultraviolet radiation chemistry, or some other pathway remains an open question, but their presence is one of several pieces of evidence suggesting that Mars once had more oxidizing surface conditions than it does today.
Manganese as a Marker of Earth’s Oxygenation
Back on Earth, manganese enrichments in ancient rocks have become one of the most debated tools for tracking when our atmosphere and oceans first became oxygen-rich. Oxidizing manganese from its soluble 2+ form to its insoluble 4+ form requires a fairly strong oxidant, and in natural environments, dissolved oxygen is the usual candidate. This led researchers to interpret ancient sedimentary layers rich in manganese oxide as signs that oxygen was present in the overlying water. A comprehensive review of the evidence argues that while alternative pathways for manganese oxidation exist, including some that do not require free oxygen, generating and preserving large sedimentary manganese enrichments effectively requires shallow oxygenated seawater. If correct, this means the manganese-rich layers found in rocks older than 2.4 billion years point to pockets of oxygen production by early photosynthetic organisms hundreds of millions of years before the atmosphere became permanently oxygenated.21Earth-Science Reviews. Manganese oxides, Earth surface oxygenation, and the rise of oxygenic photosynthesis
The connection runs even deeper when you consider that photosystem II, the biological machine that splits water and produces oxygen, depends on a manganese cluster at its catalytic core. It is a satisfying circularity: the element whose geological record may track the rise of oxygen is also the element that biology chose to catalyze the reaction producing that oxygen.
Manganese in Animal Biology and Health Risks
Animals, including humans, require trace amounts of manganese for several enzymes. The most critical of these is manganese superoxide dismutase, an antioxidant enzyme that sits inside mitochondria and neutralizes damaging oxygen radicals produced during normal energy metabolism.22PubMed Central. Manganese Superoxide Dismutase: Structure, Function, and Implications in Human Disease Manganese also contributes to bone formation, blood clotting, and the metabolism of amino acids and carbohydrates. Dietary deficiency is rare because manganese is widespread in foods like whole grains, nuts, leafy vegetables, and tea.
The health concern with manganese is almost always overexposure rather than deficiency. Workers in manganese mining, smelting, and welding who inhale manganese dust or fumes over prolonged periods can develop a condition called manganism, which involves specific damage to a brain region called the basal ganglia and produces symptoms resembling Parkinson’s disease, including tremor, stiffness, and difficulty walking.23PubMed Central. Pathophysiology of manganese-associated neurotoxicity Mining activity also releases manganese into waterways through soil erosion and runoff, raising concerns about contamination of drinking water sources in communities near mining operations.24Environmental Chemistry and Ecotoxicology. Ecotoxicological consequences of manganese mining pollutants and their biological remediation Elevated manganese in drinking water has been associated with neurodevelopmental effects in children in some epidemiological studies, though establishing firm dose-response relationships has been challenging because manganese exposure varies so widely with diet, water source, and occupation.
The fact that the same element is both biologically essential and neurotoxic at higher levels is a reminder of a pattern common across trace metals: the line between nutrient and poison is a matter of dose and route of exposure. Manganese inhaled as fine particles bypasses the gut’s regulatory mechanisms and reaches the brain much more efficiently than manganese absorbed through food, which is partly why occupational inhalation exposure is far more dangerous than dietary intake.