From The Collaborative International Dictionary of English v.0.48:
Chromium \Chro"mi*um\, n. [NL., fr. Gr. ? color.] (Chem.)
A comparatively rare element occurring most abundantly in the
mineral chromite. Atomic weight 52.5. Symbol Cr. When
isolated it is a hard, brittle, grayish white metal, fusible
with difficulty. Its chief commercial importance is for its
compounds, as potassium chromate, lead chromate, etc., which
are brilliantly colored and are used dyeing and calico
printing. Called also chrome.
[1913 Webster]