Yttrium n. : A rare metallic element of the boron-aluminium group, found in gadolinite and other rare minerals, and extracted as a dark gray powder. Symbol Y. Atomic weight, 89.

Example:
Does anyone know the density of Yttrium compared to water?

Taxonomy
yttrium, elements, compounds, oxide, isotopes, yttria, lanthanoids, yttrium oxide, Y2O3, Yttrium isotopes, neutron, metal, stable isotopes, mineral, ppm, REEs, 08-26, oxidation state.

Defination from the web:
... Yttrium (pronounced /ˈɪtriəm/) is a chemical element with symbol Y and atomic number 39. It is a silvery-metallic transition metal chemically ... See also: Category:Yttrium compounds ...