If such a coil of clay can be bent into a ring of an inch in diameter without showing any cracks, the clay can be classified as plastic clay.
Clay is commercially mined either as open strip mining or as underground mining. In open mining the clay is scraped or planed off by power machines. Kaolins or china clay is usually mined by hydraulic methods. In this process streams of water under pressure is used to remove the clay from the deposit and washed down into settling ponds.
In small scale mining operations the clay bed is first uncovered by removing soil, sand and rock so that it will not get into the clay. Then the clay is dug out with a small sharp spade. It is better to try to establish digging at a place where the clay is uniform in colour or texture over some considerable area, so that uniform results can be expected.
To be contd……
