Which of the following materials is NOT valid for performing Tayammum because it does not belong to the genus of the earth (Jins al-Ard)?

Dry Ablution (التيمم): Validity Conditions & Permissible Earth

• Pure sand (Raml).
• Soil (Turab).
• Wood (Hatab) or gold (Dhahab).
• Solid stone (Hajar).