In 1868 José Rosa Villavicencio discovered some odd blue and green deposits northeast of his ranch, which proved to be a type of high grade copper carbonate and oxides known as "boleos" due to their ball-like shape. He decided to take advantage of his discovery and sold his mineral findings to german interest out of Guaymas. A copper mine was build by them which they operated until 1885. 

On July 7, 1885 the French company El Boleo formed for the  the mining of rich deposits of copper. They acquired mineral rights to the area for 99 years, total tax exemption for 50 years and land rights to exceed 1,000,000 acres. In exchange, the company was obliged to build a town, port, and public buildings, to establish a maritime route between Santa Rosalia and Guaymas and create employment for Mexican workers. Thus, the town of Santa Rosalia was built with its wooden houses and its streets in regular blocks, unlike other towns that grew in a less planned fashion. A mining railroad and piers were built, and equipment for a smelter was transported in square-rigged sailing ships from Europe around the Cape Horn.  

The employment of Mexican workers was so successful that workers were attracted from all over. Unfortunately, there was a hidden form of exploitation as workers died of lung diseases and frequent accidents. In a single two-year period, 1,400 .workers lost their lives. Stories were told of low incomes, repressed strikes and contract abuse. Soot and gas from the smelter made the town almost uninhabitable, and there seemed to be only two choices, move the smelter or move the town. Instead, engineers worked out a unique solution, a tall stack was constructed 1/2 mile away and connected to the smelter  by a huge horizontal duct. 

In 1897 Iglesia Santa Barbara was erected. Designed by Gustave Eiffel in 1884 and pre-constructed for the World Exposition in Paris of 1889, it was purchased and shipped, unassembled across the Atlantic for assembly in Santa Rosalia.  

By the turn of the century Santa Rosalia was a major world copper producer, and a parade of square rigged ships carrying European coke to the smelter sailed up the Sea of Cortez. British ships owners, anticipating that the opening of the Panama Canal in  1914 would be unfavorable to sailing vessels, were selling off their square riggers, and the German flag ships became an increasingly common sight in Santa Rosalia. However, on August 1, 1914, Germany invaded Belgium. Three days later England declared war on Germany, and a dozen of the big German ships were interned by Mexico and spent the duration of the war swinging at anchor off the town. 

Major progress was made from 1914 - 1918 when other mining centers were opened. The mines were hot, dangerus and dirty places, "where men's hearts and bodies wilt almost as rapily as a bride's corsage," as Phillip Townsend Hanna put it. Almost 375 miles of tunnels were dug, forming a vast underground network, and more than 18 miles of narrow gage railroad track were in use.  

By 1938 production was declining and in 1954, after 53 years of continuous exploitation the mines were closed. The federal government then took over in order to provide employment for the town. It was the eve of the Santa Rosalia 100th anniversary when the mining company turned off its ovens for the last time.  
Now the town supports itself with gypsum and manganese production, tourism and marine activities. The beautiful French-style buildings have been re-modeled, the streets are paved and clean and the town boasts gardens and parks.  
Touring the town you feel the sensation of being in another space and time. You can see wooden houses with balconies and porches, the Municipal Palace, the French Hotel Frances, the Mahatma Gandhi Public Library , the Municipal DIF, the Morelos Garden where you can find one of the locomotives shipped over from Europe in 1886, as well as the ruins of the old smelting foundry. Finish your tour at the Panaderia El Boleo and enjoy the fresh boleos (rolls) and other baked goods.  
The town dresses up from October 10 - 22 each year to celebrate its founding with sports and cultural events.  
Santa Rosalia offers the visitor good hotels, restaurants and RV parks.