Cow Steer Head Pendant Carved Bone Horns Charm Rodeo Cowboy

Pulled it out of old stored stock. I know it's some kind of bone - probably cow / steer. Very Porous (see picture) Carved on the front. The black horns are of unknown material - perhaps onyx. Can't imagine there's some little horned critter this size. I must have picked it up in Tucson many years ago. It measures 2 inches long. 

Will via USPO with delivery tracking.