Pollucite

n.

1.

(Min.) A colorless transparent mineral, resembling quartz, occurring with castor or castorite on the island of Elba. It is a silicate of alumina and cæsia. Called also pollux.

Noun

1.

pollucite - a rare mineral that is an important source of cesium

atomic number 37, atomic number 55, caesium, cesium, Cs, mineral, Rb, rubidium