Africa is the second continent of the world. It is shaped like a huge unequal triangle, narrow in the south and wide in the north. It is surrounded by the Mediterranean Sea, the Red Sea, the Indian Ocean and the Atlantic Ocean. There are not many coastal islands. The largest island is Madagascar. Inhabitants of different colors in Africa, blacks, whites, and yellows, of which blacks account for about two-thirds of the total population. Africa is rich in mineral, hydro, agricultural and forestry resources. The world's most important 50 minerals are not lacking in Africa, and at least 17 of them have the highest reserves in the world. Known as the "barren land", the Sahara Desert is a huge treasure trove of energy, and there is a large amount of oil available for exploitation in the ground. South Africa is the world's largest gold producer and exporter. Zambia is known as the "country of copper mines".