What were some causes for the reach of an imperialism into West and North Africa?

Africa has an enormous amount of natural resources, such as diamonds, gold, iron, uranium, wood and other goods like fruits and more.

When European nations lost the American colonies around the 18th and 19th centuries, they were looking for other territories to restore their sources of raw materials and cheap work force, thus West and North Africa with the abundance of minerals and other natural resources was their answer.

Nations like France needed to enhance their economy and recover from the great depression at that time, reason why they clashed against the British in West Africa; and European missionaries supported the idea believing imperialism would create the conditions for missionary activity since they believed themselves superior to African cultures, then entitlement and pride also pushed them towards it.