Alms Tax: Melting Gold and Silver Coins in the Twelfth Month
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 1920
If a person melts gold and silver coins in the twelfth month, he must give zakat on them. If as a result of melting the coins their weight or value decreases, he must give the amount of zakat that was obligatory for him prior to melting them.
-Ayatullah Sistani, Practical Laws of Islam, Alms Tax (Zakat)