What are FOUR examples of raw materials that Europeans hoped to obtain by conquering lands in Africa?

We can look at the example of the Belgian Congo to isolate various raw materials that were taken and exported from this country. The key export from the Belgian Congo in its early days was rubber, which could not be produced in Europe. The British Empire found this material in their southeast Asian colonies, after which there was less demand for rubber from the Congo.
This caused the Belgians to increase production of a second raw material: copper. Copper mining in the Congo was extensive during the period of occupation.
Other raw materials obtained by the Belgians in the Congo included diamonds, gold, and palm oil. All of these materials were also extracted from other colonized African nations by other European powers, as they were necessary for the adequate functioning of things at home in Europe.