iztacayotl. blancura. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 49r. col. 1. Thanks to Joe Campbell for providing the transcription.
Frances Karttunen:
IZTĀCĀYŌ-TL the white of an egg / clara (de huevo) (T) [(1)Zp. 171]. Z fails to mark A long, and T has a short vowel and postvocalic glottal stop in the third syllable. M has iztacayotl ‘ whiteness,’ which is probable derived simple from IZTĀCĀ- (the compounding form of ĪZTĀC) and –YŌ. See IZTĀC, ĀYŌ-TL Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 124.