Yttrium is a chemical element with symbol Y and atomic number 39. It is a silvery-metallic transition metal chemically similar to the lanthanoids and has historically been classified as a rare earth element. Yttrium is almost always found combined with the lanthanoids in rare earth minerals and is never found in nature as a free element. Its only stable isotope, 89Y, is also its only naturally occurring isotope. In 1787, Carl Axel Arrhenius found a new mineral near Ytterby in Sweden and named it… (More on Yttrium)