Purity: Alternative Materials for Tayammum

Practical Laws of Islam as per the teachings of Ayatullah Sistani

Ruling 674:

Tayammum performed with gypsum or limestone is valid. Similarly, tayammum performed with dust that gathers on carpets, clothing, and similar things is also valid provided that its quantity is such that it can commonly be considered to be very fine soil, although the recommended precaution is that if alternatives are available, one should not perform tayammum with dust. Similarly, based on recommended precaution, if alternatives are available, one should not perform tayammum with gypsum and limestone that have been baked, nor with brick that has been baked, nor with mineral stones such as agate (ʿaqīq).

-Ayatullah Sistani, Practical Laws of Islam, Purification (Taharah)