Is it permissible to perform Tayammum using snow, gypsum, or rock that has no dust?
Chapter on Tayammum
Al-Mughni
Book of Purification
Primary text
Imam Malik and Imam Abu Hanifa permitted Tayammum using a rock devoid of dust and damp earth from which no dust adheres to the hand. Imam Malik specifically permitted Tayammum using snow, gypsum, and anything that rises up from the surface of the earth.
Supporting text
Imam Malik disallowed Tayammum using the dust from bedding and clothing because the Prophet, peace be upon him, blew on his hands after striking them.