Short answers, pulled from the story.
Johan Gottlieb Gahn isolated manganese metal in 1774 by reducing manganese dioxide with carbon. This discovery occurred after manganese had been used for centuries as a glassmaking additive to remove green tints caused by iron impurities.
Ancient cave painters in Gargas, France used manganese dioxide as a pigment to create art 30000 years ago. These cave paintings from the period between 30000 and 24000 years old are made from the mineral form of manganese dioxide pigments.
Manganese nodules found on the ocean floor are composed of 29% manganese. According to a 1978 estimate, the ocean floor contains 500 billion tons of these manganese nodules.
British academic James Couper first described manganism in 1837 after studying two patients who were manganese grinders. The disorder presents with symptoms resembling Parkinson's disease but is not responsive to L-DOPA treatment.
The real mission of the Hughes Glomar Explorer was to raise a sunken Soviet submarine known as K-129 to retrieve Soviet code books. The ship used a cover story about harvesting manganese nodules from the sea floor to hide this operation.