Short answers, pulled from the story.
Manganese is a chemical element with the symbol Mn and atomic number 25, a hard, brittle, silvery metal first isolated in the 1770s. It is essential to iron and steel production for its sulfur-fixing, deoxidizing, and alloying properties, and it also appears in aluminium beverage-can alloys, batteries, fertilizers, pigments, and as an essential human dietary element.
The name traces back to two black minerals from the lands of the Magnetes, both called magnes. The non-magnetic ore used to decolorize glass became magnesia nigra, which 16th-century glassmakers called manganesum, and the Italian physician Michele Mercati called it manganesa before the metal drawn from it became manganese.
The human body contains about 12 milligrams of manganese, mostly in the bones. The remainder concentrates in the liver and kidneys, and in the brain it binds to manganese metalloproteins, most notably glutamine synthetase in astrocytes.
Manganism is a rare neurological disorder caused by excessive manganese ingestion or inhalation, first described in 1837 by British academic John Couper. Its late stage resembles Parkinson's disease, but unlike Parkinson's it is not associated with loss of smell and patients are typically unresponsive to L-DOPA.
In 1972 the CIA's Project Azorian, channeled through billionaire Howard Hughes, commissioned the ship Hughes Glomar Explorer under the cover story of harvesting manganese nodules from the sea floor. The real mission was to raise the sunken Soviet submarine K-129 and retrieve its code books.
About 80 percent of known world manganese resources are in South Africa, and the country topped all other nations by producing 3.4 million tons in 2011. Other mining nations include Australia, China, Gabon, Brazil, India, Kazakhstan, Ghana, Ukraine, and Malaysia.