Short answers, pulled from the story.
Eugène-Anatole Demarçay successfully isolated the new element in 1901. He had examined spectral lines from samarium-gadolinium concentrates starting in 1896 and suspected contamination with an unknown substance.
Isotope 153Eu holds 52.2% natural abundance while 151Eu accounts for the remainder. Natural europium consists of these two isotopes found in almost equal proportions.
The Bayan Obo iron ore deposit in Inner Mongolia contains significant amounts of bastnäsite and monazite holding an estimated 36 million tonnes of rare-earth element oxides. Mining operations at this location made China the largest supplier during the 1990s.
Color television screens contain between 0.5 and 1 gram of europium oxide. Trivalent europium produces red phosphors used extensively in CRT displays.
The +2 state provides stability through a half-filled f-shell electron configuration. Magnetic measurements suggest these metals are effectively divalent while others remain trivalent.