Greenstone, probably jadeite
Long after the demise of the Olmecs, Mesoamerica's earliest major civilization, which dominated the Gulf Coast of Mexico from ca. 1500 to 400 B.C., their art objects were prized as relics of fabled antiquity by the civilizations that later rose to power in the region, such as the Maya and the Aztecs. This head originally belonged to an entire figure, but the body was apparently decapitated at some point, after which the head was repolished and drilled with a large suspension hole in order to function as a pendant. The facial features---a strong downturned mouth, broad nose, and almond-shaped eyes---are typical of Olmec art. This physiognomy conforms to the human ideal favored by the Olmecs and sometimes also characterizes their gods.
Handbook of the Collections (New Haven, Conn.: Yale University Art Gallery, 1992), 313, ill.
Mary Miller, “Precolumbian Art of Mexico and Central America at the Yale University Art Gallery,” Yale University Art Gallery Bulletin (199596): 20, fig. 2.
Susan B. Matheson, Art for Yale: A History of the Yale University Art Gallery (New Haven, Conn.: Yale University Art Gallery, 2001), 16869, fig. 168.
Mary Miller, The Art of Mesoamerica: From Olmec to Aztec, 5th ed. (London: Thames and Hudson, 2012), 413, fig. 31.