English is the official language of Sierra Leone, though Krio is spoken by 97% of the population and unites the various ethnic groups. Sierra Leone has a multi-party political system with a directly elected president and unicameral legislature. The majority religion is Islam at 71.3% of the population, with the two largest ethnic groups being the Temne and Mende. Sierra Leone relies on mining, especially diamonds, for its economic base and has large deposits of rutile used in paint pigments and welding rods.