Step 1: Defining Ball Clay.
Ball clay is a fine-grained, highly plastic, sedimentary clay, recognized for its exceptional plasticity and common application in ceramic pottery.
Step 2: Evaluating Choices.
- (1) Sedimentary Clay: Incorrect. While ball clay is sedimentary, its defining characteristic is high plasticity, not just its origin.
- (2) Plastic Clay: Correct. Ball clay falls under the classification of plastic clay due to its significant plasticity, which facilitates shaping and molding.
- (3) Coloured Clay: Incorrect. Color is not a typical attribute associated with ball clay.
- (4) Residual Clay: Incorrect. Residual clay originates from weathering processes and is distinct from ball clay.
Step 3: Determining the Correct Answer.
Therefore, the accurate classification is (2) Plastic Clay.