Short answers, pulled from the story.
Carl Gustaf Mosander discovered lanthanum in 1839 while attempting to purify cerium nitrate. He named the element lanthanum from the Greek word lanthanein meaning to lie hidden because it had been lurking within the cerium sample all along.
Pure lanthanum metal was first isolated in 1923 nearly a century after its initial discovery in 1839. The element remained elusive for decades because its chemical properties were so similar to cerium that it could not be separated easily.
Lanthanum is the 28th most abundant element in the Earth's crust and is almost three times as abundant as lead. It is found in minerals such as monazite and bastnäsite where it composes about a quarter of the lanthanide content.
Lanthanum is used as an anodic material in nickel-metal hydride batteries and in hydrogen sponge alloys capable of storing up to 400 times their own volume of hydrogen gas. Mischmetal containing 25% to 45% lanthanum is used in lighter flints and as an anodic material in batteries.
Lanthanum has no known biological role in humans but is used by some bacteria as a cofactor for the methanol dehydrogenase of the methanotrophic bacterium Methylacidiphilum fumariolicum SolV. It is used as a phosphate binder in cases of end stage renal disease and as an electron-dense tracer in molecular biology.
The price of lanthanum oxide rose steeply to $140,000 in mid-2011 and fell back to $38,000 by early 2012. The Institute of Rare Earths Elements and Strategic Metals reported these figures for a metric ton of 99% lanthanum oxide FOB China.