What are some things that the element yttrium is in?

Answer 1

High temperature superconductors.

Answer 2

In nature, yttrium and the other rare-earth elements are usually found mixed together in minerals like monazite sands. Being chemically similar it's quite hard to separate them. Yttrium was discovered in Sweden, but it's found in many other places. It's used in lasers, semiconductors, superconductors and glasses. The flint that makes the spark in some cigarette lighters is made of rare-earth elements.