Rasendracudamani 11.3

11.3

{sulfur:: yellow}
tathā cāmalasāraḥ syād yo bhavetpītavarṇavān /
śukapicchaḥ sa eva syācchreṣṭho rasarasāyane //

And likewise there is amalasāra, which is of a yellow colour;
It is called parrot's tail-feather, and is the best in mercurial rejuvenation therapy;