Rasarnava 6.33

6.33

kṛṣṇābhrapatraṃ saṃgṛhya pīlutailena lepayet
saptāhamātape taptam āmle kṣiptvā dinatrayam //

Taking sheets of black mica, one should smear them with pīlu oil; / heated in the sun for seven days, thrown into sour [liquid] for three days;