Manganese
Manganese carries the atomic number 25 and exists as a hard, brittle, silvery metal. Its most common form is the stable isotope known as 55Mn. Scientists have isolated several radioisotopes ranging from 46Mn to 72Mn. The longest-lived radioactive version is 53Mn with a half-life of 3.7 million years. Another notable isotope is 54Mn which decays in 312.08 days. A third major variant is 52Mn that lasts for 5.591 days before breaking down. All other radioactive forms disappear in less than three hours. Most of these unstable versions vanish within one minute. Lighter isotopes decay through electron capture while heavier ones undergo beta decay. Three meta states also exist alongside the standard forms. This element belongs to the iron group synthesized in massive stars before supernova explosions. The decay of 53Mn into 53Cr helps date early Solar System events. Variations in Mn/Cr ratios found in meteorites suggest non-zero initial 53Mn/55Mn ratios. These findings support evidence from 26Al and 107Pd regarding planetary formation. Four distinct structural forms called allotropes exist at different temperatures. Alpha manganese remains stable at room temperature with a complex unit cell containing 58 atoms. Beta manganese appears when heated above a specific transition point. Gamma manganese forms above another threshold but converts back to beta if cooled quickly. Delta manganese exists only at very high temperatures near the melting point.
Ancient miners identified two black minerals from regions known as Magnetes. One male ore attracted iron and became known as lodestone or magnetite. The female ore did not attract iron but decolorized glass. Glassmakers later called this female mineral magnesia nigra. Italian physician Michele Mercati renamed it manganesum around the 16th century. Swedish chemist Johan Gottlieb Gahn isolated an impure sample of pure metal in 1774. He achieved this by reducing manganese dioxide with carbon. Ignatius Gottfried Kaim may have done similar work earlier but records remain uncertain. Alchemists used manganese dioxide to produce chlorine gas starting in the mid-18th century. Carl Wilhelm Scheele utilized pyrolusite for these experiments. British academic James Couper noted health issues among miners in 1837. He linked heavy exposure to a form of Parkinson's disease. Steelmaking patents appeared around the beginning of the 19th century. Robert Forester Mushet introduced spiegeleisen to steel processes in 1856. This alloy improved hardness without increasing brittleness. Cave paintings in Lascaux France use manganese-based pigments dating back thousands of years. Paintings in Gargas span 30,000 to 24,000 years old. Egyptian and Roman glassmakers added compounds to remove color from their creations. The Leclanché cell invention in 1866 increased demand for manganese dioxide batteries. A CIA operation called Project Azorian attempted to recover manganese nodules in 1972. The real mission involved retrieving Soviet code books from sunken submarine K-129.
Manganese plays an essential role in iron and steel production worldwide. About 85% to 90% of total manganese demand goes toward steelmaking. Small amounts improve workability at high temperatures by forming sulfides. If content reaches 4%, embrittlement becomes dominant until concentrations hit 8%. Steel containing 8 to 15% manganese achieves tensile strength up to 863 MPa. Robert Hadfield discovered a specific alloy with 12% manganese in 1882. This material remains known as Hadfield steel or mangalloy today. British military helmets used this strong metal during World War I. U.S. forces adopted it later for combat gear. Aluminum alloys contain roughly 1.5% manganese for corrosion resistance. These alloys absorb impurities that would otherwise cause galvanic corrosion. Beverage cans utilize aluminum grades 3004 and 3104 containing between 0.8 and 1.5% manganese. Over 1.6 million tonnes of these alloys were consumed before the year 2000. That usage required approximately 16,000 tonnes of pure manganese. Copper alloys like Manganin appear in shunt resistors measuring large currents. These metals maintain low temperature coefficients and resist sulfur damage. They function well in harsh automotive environments. Methylcyclopentadienyl manganese tricarbonyl serves as an anti-knock compound in gasoline. It boosts octane ratings while reducing engine knocking. The United States minted wartime nickels from 1942 to 1945 using manganese. These coins contained 56% copper, 35% silver, and 9% manganese. Modern dollar coins since 2000 feature brass with 7% manganese.
Manganese makes up about 1000 parts per million of Earth's crust. It ranks as the 12th most abundant element globally. Soil contains between 7 and 9000 ppm with an average near 440 ppm. Pyrolusite remains the primary ore found in nature. Other important minerals include braunite, psilomelane, and rhodochrosite. Approximately 80% of known world resources lie within South Africa. Major deposits also exist in Ukraine, Australia, India, China, Gabon, and Brazil. Hotazel in the Northern Cape Province holds vast identified deposits. A 2011 estimate placed these reserves at 15 billion tons. South Africa produced 3.4 million tons in that same year. Ocean floors contain abundant manganese nodules composed of 29% manganese. An estimated 500 billion tons sit on the seabed according to 1978 data. No commercial harvesting method has succeeded despite ongoing attempts. Dissolved manganese originates from hydrothermal vents throughout global oceans. Ninety percent comes directly from these underwater sources. Particulate matter develops buoyant plumes over active vent sites. Surface concentrations rise due to river inputs and dust deposition. Coastal sediments usually show lower levels but increase from industrial discharges. Hydrothermal vents release fluid enriched with dissolved manganese into surrounding waters. This fluid can travel up to 4,000 kilometers via microbial capsules. Levels remain higher when oxygen content drops significantly. Production processes mix ore with iron and carbon in blast furnaces. Electric arc furnaces handle similar reductions for ferromanganese creation. The resulting product contains between 30 and 80% manganese. Heap leaching offers a progressive extraction alternative using natural gas heat. This method reduces all ore to Manganese oxide before grinding it further.
Manganese acts as an essential dietary element for human survival. The body holds about 12 mg mostly within bone structures. Soft tissue concentrates the remainder in liver and kidneys. Brain cells bind manganese to metalloproteins like glutamine synthetase. Dozens of proteins rely on this metal as a critical component. Enzymes such as arginase and superoxide dismutase contain manganese cofactors. Photosystem II houses four manganese atoms in its oxygen-evolving complex. This cluster catalyzes water oxidation during plant light reactions. It produces the oxygen released by vegetation globally. Reverse transcriptases found in many retroviruses utilize manganese centers. Diphtheria toxin and lectins also incorporate these polypeptides. Macronutrient metabolism depends heavily on manganese presence. Bone formation requires adequate levels throughout development. Free radical defense systems utilize manganese enzymes for protection. Deficiency causes skeletal deformation in animals and inhibits collagen production. Wound healing slows significantly without sufficient intake. Children aged one to three need 1.2 mg daily according to U.S. guidelines. Pregnant women require 2 mg while lactating mothers need 2.6 mg. European Food Safety Authority sets adult requirements at 3.0 mg per day.
Excessive exposure leads to manganism, a rare neurological disorder. Symptoms resemble Parkinson's disease but respond differently to treatment. British academic John Couper first described the condition in 1837. He studied two patients who worked as manganese grinders. Early stages involve depression, mood swings, and compulsive behaviors. Late-stage symptoms include weakness, tremors, and forward-leaning gait. Patients often cannot walk backward without falling. Rigidity affects dexterity and balance permanently. Unlike Parkinson's, sense of smell remains intact here. Brain levels return to normal yet symptoms worsen over time. Manganese accumulates in basal ganglia causing abnormal movements. A mutation of SLC30A10 gene links directly to this disease. Lewy bodies typical of Parkinson's do not appear in these cases. Animal experiments show manganese induces mouse-killing behavior in rats. Breathing air with more than 5 micrograms per cubic meter causes symptoms. OSHA limits workplace exposure to 5 mg/m3 over eight hours. NIOSH recommends a stricter limit of 1 mg/m3 daily. Levels reaching 500 mg/m3 become immediately dangerous. Waterborne manganese shows greater bioavailability than dietary sources. Higher drinking water levels correlate with reduced intelligence quotients in children. Up to 8.7 million Americans face potential risk from shower water inhalation. Marine organisms accumulate manganese during hypoxic periods since 1990. Fish, crustaceans, mollusks, and echinoderms suffer immune system suppression. Pathogen resistance declines when manganese levels rise excessively.
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Common questions
What is the atomic number of manganese?
Manganese carries the atomic number 25 and exists as a hard, brittle, silvery metal. Its most common form is the stable isotope known as 55Mn.
When did Johan Gottlieb Gahn isolate pure manganese metal?
Swedish chemist Johan Gottlieb Gahn isolated an impure sample of pure metal in 1774 by reducing manganese dioxide with carbon. Ignatius Gottfried Kaim may have done similar work earlier but records remain uncertain.
How much manganese is required daily for children aged one to three years?
Children aged one to three need 1.2 mg daily according to U.S. guidelines. Pregnant women require 2 mg while lactating mothers need 2.6 mg.
Where are the largest known reserves of manganese located globally?
Approximately 80% of known world resources lie within South Africa. Hotazel in the Northern Cape Province holds vast identified deposits with a 2011 estimate placing these reserves at 15 billion tons.
Why does excessive exposure to manganese cause manganism?
Excessive exposure leads to manganism because manganese accumulates in basal ganglia causing abnormal movements and symptoms resembling Parkinson's disease. Breathing air with more than 5 micrograms per cubic meter causes symptoms.