Short answers, pulled from the story.
William Hyde Wollaston discovered rhodium in 1803. He isolated the metal by dissolving crude platinum ore from South America in aqua regia and observing a rose-red precipitate when adding sodium chloride to the solution.
Rhodium is essential for modern environmental protection because it is the only metal capable of efficiently reducing nitrogen oxides to harmless nitrogen and oxygen in three-way catalytic converters. By 2012, 81 percent of the 30,000 kilograms of rhodium consumed worldwide was used in these converters to control vehicle emissions.
Rhodium functions in the chemical industry as a catalyst for the Monsanto process to produce acetic acid and for hydroformylation to convert alkenes into aldehydes. It also facilitates asymmetric hydrogenation to form drug precursors and aids in the production of fiberglass and flat-panel glass.
The primary use of rhodium in the jewelry industry is electroplating onto white gold and platinum to create a brilliant, reflective white surface known as rhodium flashing. This thin layer protects the underlying metal from tarnishing and enhances its luster, though it requires periodic re-plating as it wears away.
Rhodium neutron detectors are used in nuclear reactors to measure neutron flux levels and generate three separate signals to create a three-dimensional picture of reactivity within the reactor core. For example, the Palo Verde nuclear reactors each contain 305 rhodium neutron detectors to ensure the reactor operates at peak efficiency.
The majority of the world's rhodium is produced in South Africa, which accounts for approximately 80 percent of global production. Russia and the Sudbury region of Ontario, Canada, follow as the next principal sources, with an annual world production of only 30 tonnes.