Short answers, pulled from the story.
Carl Axel Arrhenius discovered yttrium in 1787 when he found a heavy black rock in an old quarry near the Swedish village of Ytterby. Johan Gadolin identified the new oxide within the mineral in 1789, and Anders Gustaf Ekeberg confirmed the identification in 1797. Friedrich Wöhler first isolated the metal in 1828 by reacting a volatile chloride with potassium.
Yttrium exists in nature never as a free element but always locked in combination with lanthanide elements within rare-earth minerals. The element is found in soil in concentrations between 10 and 150 parts per million and in sea water at 9 parts per trillion. It is the 43rd most abundant element in the Earth's crust at about 31 parts per million.
Yttrium in the Solar System was created by stellar nucleosynthesis mostly by the s-process which accounts for approximately 72% of its existence. The s-process is a slow neutron capture of lighter elements inside pulsating red giant stars such as Mira. The r-process accounts for the remaining 28% and consists of rapid neutron capture by lighter elements during supernova explosions.
The most important present-day use of yttrium is as a component of phosphors especially those used in LEDs and television set cathode ray tube displays. Yttrium is a key ingredient in the yttrium barium copper oxide superconductor developed at the University of Alabama in Huntsville and the University of Houston in 1987. The radioisotope yttrium-90 is used to label drugs for the treatment of various cancers including lymphoma and leukemia.
In 2009 Professor Mas Subramanian and associates at Oregon State University discovered that yttrium can be combined with indium and manganese to form an intensely blue pigment known as YInMn blue. This was the first new blue pigment discovered in 200 years and is intensely blue non-toxic inert and fade-resistant. The pigment is formed by heating yttrium indium and manganese oxides together resulting in a crystalline structure that absorbs light to produce a vivid blue color.
Yttrium can be highly toxic to humans animals and plants with water-soluble compounds considered mildly toxic while insoluble compounds are non-toxic. The Occupational Safety and Health Administration limits exposure to yttrium in the workplace to 5 milligrams per cubic meter over an 8-hour workday. At levels of 50 milligrams per cubic meter yttrium is immediately dangerous to life and health.