The democratic republic of the congo possesses vast reserves of

copper
iron
gold
uranium

 Copper

Explanation: The Democratic Republic of the Congo has vast reserves of minerals. It is the main producer of copper in the African continent Among the most abundant minerals are copper, tin gold, cobalt, diamonds, uranium and coltan. In this country there is a great variety of mines, through which the trade of these minerals is maintained. Apart from copper, cobalt and coltan are also the minerals that are found with the greatest reserves in the Republic of the Congo compared to other countries worldwide.

i think it's a but not entirely sure