Scandium, periodic table Sc, is a metal. It has 21 protons and its most common isotope has 24 neutrons for an atomic mass of 45.
Scandium is rare in the Earth and Martian crusts. Production on Earth is of the order of 20 tonnes per year, mostly as an agent to improve certain aluminum alloys for aerospace.
- Wikipedia: https://en.wikipedia.org/wiki/Scandium