1911 Encyclopædia Britannica/Ixtaccihuatl

IXTACCIHUATL, or Iztaccihuatl (“white woman”), a lofty mountain of volcanic origin, 10 m. N. of Popocatepetl and about 40 m. S.S.E of the city of Mexico, forming part of the short spur called the Sierra Nevada. According to Angelo Heilprin (1853–1907) its elevation is 16,960 ft.; other authorities make it much less. Its apparent height is dwarfed somewhat by its elongated summit and the large area covered. It has three summits of different heights standing on a north and south line, the central one being the largest and highest and all three rising above the permanent snow-line. As seen from the city of Mexico the three summits have the appearance of a shrouded human figure, hence the poetic Aztec appellation of “white woman” and the unsentimental Spanish designation “La mujer gorda.” The ascent is difficult and perilous, and is rarely accomplished.

Heilprin says that the mountain is largely composed of trachytic rocks and that it is older than Popocatepetl. It has no crater and no trace of lingering volcanic heat. It is surmised that its crater, if it ever had one, has been filled in and its cone worn away by erosion through long periods of time.