Mexico produced this proof bullion coin as part of their Pre-Columbian Teotihuacan series. This 1 New Peso (1/4 Onza) - 0.25 Troy Ounce coin carries a likeness of a death mask (Disco De La Muerte).
The 1998 dated coins have a mintage of ONLY 500 Proofs! A tough coin to find! Listed in Krause as KM#617.