Mining played a prominent role in the development of the New World. The Spanish march northward from Central Mexico was fueled by successive discoveries of silver at Zacatecas, Taxco, and Fresnillo and then at Durango and Santa Barbara. These were huge silver deposits. Silver from these mines powered the economy of the Spanish Empire.
By the early 1700’s, Spanish prospectors were wandering the mountains and deserts of Sonora and southern Arizona. And then in 1736, a most unusual discovery occurred in the area between Guevavi and the Opata Indian village called Arissona. It was in that year that a Yaqui Indian found chunks of pure silver lying right on the surface of the ground. This “place where silver grew out of the ground” eventually became known as the “Planchas de Plata” or “Bolas de Plata” and produced some truly monumental silver nuggets, sheets, and boulders. One huge surface boulder of pure silver weighed nearly 3000 pounds. Many chunks weighing hundreds of pounds were discovered in the inevitable rush that followed. But the surface deposits gave out in only 5 years. By 1741, the area was abandoned.
The border country of Arizona and Sonora is silver country. For many years, persistent rumors of another surface deposit of native silver have circulated throughout the area. In the 1850’s, chunks of native silver were again appearing at the trading post in Tubac. The local Opata Indians were selling them to the trader. Apparently the Opatas had discovered a new source of silver.
In the early 1880’s, huge nuggets of native silver again began to turn up in the area. There was certainly no denying the chunks of silver lying on the bar of John Connor’s saloon in Nogales. It was Opata silver alright. An old Opata Indian had sold the nuggets to a prospector who brought them in to Nogales. The Opata claimed he had found the nuggets just lying on the surface while hunting along Carrizo Creek, northwest of Nogales. It was another “Planchas de Plata”!
The prospector immediately set out for the desert country around Carrizo Creek, which drains the Atascosa Mountains west of the town of Rio Rico. Months later, he returned to Nogales with his burros straining under a load of silver. The old prospector had found the silver nuggets eroding out of a clay “hardpan” somewhere near Carrizo Creek. Unfortunately, the old man died before he could return to the silver field. John Connors made many prospecting trips into the desert in search of the silver but never found it.
This article is courtesy of http://www.thegeozone.com