Answered by Shaykh Faraz Rabbani
I follow the Hanafi mabhab, and my husband, until a few years ago, followed the Shafii. Recently, I have begun to need to make tayammum. At this time, my husband expressed concern that I may have made it incorrectly because I assumed that a rock, for instance, does not get used up as water does. (Going from purifying to just pure). He expressed this because it was the ruling he knew from his former school. Also, is dust any dirt or earth?
Walaikum assalam wa rahmatullahi wa barakatuh,
I pray this finds you in the best of health and spirits. In the Hanafi school, it is valid to make tayammum with anything that is naturally of the top surface of the earth–including sand, soil, and stones. [ Shurunbulali, Maraqi al-Falah ] And it is valid to make tayammum repeatedly from the same surface–unlike water, the surface doesn’t become “used.” [ibid.]
And Allah alone gives success.
Faraz Rabbani