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 is located on the west coast of Africa and has a tropical climate with rainy and dry seasons. The economy relies heavily on mining, especially diamonds and rutile.