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 a Rare Earth element. However, it is fairly common in the Earth crust (35th most common element), but rarely concentrated in minerals. this is likely to be true as well in the Martian crust. Production on Earth is of the order of 20 tonnes per year, mostly as an agent to improve certain aluminum alloys for aerospace.
Production on Mars
It is likely to be imported from Earth for quite some time. However, due to it's relative cosmic abundance, if it is needed it could be extracted from asteroids, or anywhere on the Martian crust at relatively high processing costs.
- Wikipedia: https://en.wikipedia.org/wiki/Scandium