Scandium is a chemical element with symbol Sc and atomic number 21. Its also silvery and white.
The element is surprisingly rare. It is the scarcest element between Cl and Fe by a full order of magnitude. The last two stages of fusion in massive stars are the oxygen-burning process(1), which produces elements in the silicon-sulfur group, and the silicon-burning process, which produces iron-group elements(2). Scandium is too large (Z or A) to be produced efficiently in the former and too small to be produced efficiently by the latter.
REFERENCES
- "Oxygen Burning Process" and "Silicon Burning Process"; both in Wikipedia