Things on which Tayammum is allowed

692. Tayammum can be done on earth, sand, lump of clay or stone, but, as per recommended precaution, if earth is available Tayammum should not be performed on anything else. If earth is not available, then it can be performed on sand, and if sand is not available then it can be performed on a lump of clay, and if even a lump of clay is not available then it can be performed on a stone.