Juan Maria Antonio Rivera (also spelled Ribera) was an 18th century Spanish explorer who explored southwestern North America, including parts of Southern Rocky Mountains. In 1765, at the request of Governor Tomás Vélez Cachupin of New Mexico, he led an expedition from Santa Fe northward through present-day Utah and Colorado, partly in search of gold but also to help thwart the expansion of other European powers in the region. His expedition passed through regions inhabited by the Ute tribes. It followed the Dolores River (a tributary of the Colorado River), which he may have named. The ore samples he brought back to Santa Fe were among the first recorded discoveries of gold in present-day Colorado, although they created no particular interest at the time.