Kautilya's Arthashastra 2.13.9

2.13.9

ākarodgataṃ sīsānvayena bhidyamānaṃ pākapattrāṇi kṛtvā gaṇḍikāsu kuṭṭayet, kadalīvajrakandakalke vā niṣecayet //

Mine gold which is brittle owing to its contamination with lead shall be heated wound round with cloth (pákapatráni kritvá); and hammered on a wooden anvil. Or it may be drenched in the mixture made of mushroom and vajrakhanda (Antiquorum).