Argentine Man's Hat

This hat is the traditional leather hat of the gaucho.

The men who work the cattle on the Pampas, the vast grasslands of Argentina, are called gauchos, from the Quechua huachu, which means orphan or vagabond. From the mid-18th to the mid-19th centuries, the early gauchos were skilled horsemen, living off the land and tracking down lost cattle for ranchers, their patrons for whom they also provided protection, and in times of battle, military service.

The gaucho costume, still worn by modern Argentine cowhands, reflected their life on horseback: a wide-brimmed hat, a belt, a woolen poncho, accordion-pleated trousers, and leather boots.
 
Source:
http://www.gauchoclothes.com/hats.html
http://gosouthamerica.about.com/od/argartcultureentertain/a/gauchos.htm