This is a vintage 1977 or 1978 Raintree enameled brass belt buckle with excellent detailing, featuring a brown 3D Texas longhorn steer skull. The buckle measures 3-1/2"W X 2-3/4"L and will fit up to a 2" belt. 
http://www.etsy.com/listing/86050421/vintage-belt-buckle-raintree-enameled