Purity: Prohibited Materials for Shrouding
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 568:
It is not permitted to shroud a corpse with anything impure or with pure silk cloth; and based on obligatory precaution, [it is not permitted to shroud a corpse] with cloth that has been woven with gold. However, there is no problem in using these if no other option is available.
-Ayatullah Sistani, Practical Laws of Islam, Purification (Taharah)