Juan María Antonio de Rivera (also spelled Ribera) was an 18th-century Spanish explorer who explored southwestern North America, including parts of the Southern Rocky Mountains. In 1765, at the request of Governor Tomás Vélez Cachupin of New Mexico, he led two expeditions from Santa Fe northward through present-day Colorado and Utah, partly in search of silver but also to help thwart the expansion of European powers in the region. His expeditions passed through regions inhabited by the Ute and Southern Paiute tribes. Rivera camped with Paiutes along the Dolores River in July 1765 before returning to Santa Fe for supplies. His second trip set out in September 1765 with an explicit instruction from Governor Cachupin to find where the Natives cross the Colorado River.[1] Although his diaries of the expedition do not state when the party returned to Santa Fe, he signed and certified his second diary 20 November 1765. His expedition crossed the Animas River near present-day Durango, Colorado (a tributary of the Colorado River), which he may have named.[2] 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.
Jacobs, G. C. 1992. "The Phantom Pathfinder" Utah Historical Quarterly 60(3): 201 - 223.