[AS.] A fine-grained, sandy substance, derived from the decay of aluminium silicates. It is white when pure, but it is generally mixed with impurities which impart to it various shades of gray, brown, red, purple, or blue. When dry it is friable, and when wet can be kneaded between the fingers. When shaken with water it becomes mud. It is largely used for making bricks and earthenware.