Manganese easy to oxidize. Manganese metal and its common ions are paramagnetic. Manganese tarnishes slowly in air and oxidizes ("rusts") like iron in water containing dissolved oxygen. Naturally occurring manganese is composed of one stable isotope, Mn. Eighteen radioisotopes have been isolated and described, ranging in atomic weight from 46 u (Mn) to 65 u (Mn). The most stable are Mn with a half-life of 3.7 million years, Mn with a half-life of 312.3 days, and Mn with a half-life of 5.591 days. All of the remaining radioactive isotopes have half-lives of less than three hours, and the majority of less
Manganese alloyed with manganese was harder but not more brittle. In 1837, British academic James Couper noted an association between miners' heavy exposure to manganese with a form of Parkinson's disease. In 1912, United States patents were granted for protecting firearms against rust and corrosion with manganese phosphate electrochemical conversion coatings, and the process has seen widespread use ever since. The invention of the Leclanché cell in 1866 and the subsequent improvement of batteries containing manganese dioxide as cathodic depolarizer increased the demand for manganese dioxide. Until the development of batteries with nickel-cadmium and lithium, most batteries contained manganese. The zinc-carbon