Placer mining
In some cases, minerals occur as placer deposits , the original bearing rock having been broken down by the natural processes of erosion, and transported , and redeposited by running water. For example particles of gold, tin, or platinum may occur in the sands and gravels in the beds of some rivers.
Placer mining in a river
The deposits are recovered by panning which involves digging out the sand, swirling it around with water in a shallow pan. The lighter sand is washed over the side, leaving the heavier mineral at the bottom of the pan.
This type of mining requires very little in the way of equipment and is usually carried out by individual miners. A more advanced form of placer mining is known as Dredging which is shown in the picture below.
Activity
(a) (i) What is mining?
Identify the types of minerals and factors determining the distribution of minerals.
(ii) Name three main methods of mining.
(b)(i) Describe how each of the methods of mining is used in Africa.
(ii) Name the main minerals found in Africa.
(c)(i) "Africa is endowed with various minerals but they have not been fully exploited".
Give reasons for this.
(ii) What are the effects of mining on the environment?
POSSIBLE ANSWERS:
(a) (i) Mining refers to the extraction of mineral resources from the ground for man's own benefit.