Tilak, the U-shaped marking in pale yellow color, found on the foreheads of devotees of Krishna around the world, is called Gopi Chandan. The devotees in ISKCON apply it in 12 places on their bodies every day.
 
It is said in the Padma Purana that because this clay is so supremely pure, if one is wearing this Gopi Chandan while performing Yajnas, Homas, or other Vedic rites, even if mantras are chanted without proper pronunciation or an error is made in the ritual, one will still get the full benefit of those acts.
 
Some people say this tilak still carries the fragrance of transcendental substances.