hot ash from a wax candle (see Molina)
xicocuitlaocotl yyectiloca. pauesa dela dicha candela. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 159r. col. 1. Thanks to Joe Campbell for providing the transcription.