Cerro Colorado, Arizona: Murder, Lost Silver, and the Father of Arizona

01Charles Poston and the Sonora Exploring & Mining Company

Spanish explorers first discovered silver in these hills around 1750, and Mexican prospectors worked the surface deposits for decades using Pima and Papago Indian labor. After the Gadsden Purchase transferred the land to the United States in 1854, Charles Debrille Poston — later known as the "Father of Arizona" — arrived and established a mining operation near the old deposits.

Poston partnered with Major Samuel P. Heintzelman, commander of Fort Yuma, and together they raised $2 million from Cincinnati investors to found the Sonora Exploring and Mining Company on March 24, 1856. Heintzelman served as president and Poston as managing supervisor, headquartering operations at nearby Tubac.

The Heintzelman Mine — also called the Silver Queen — became the district's prize. Early ore ran $5,000 to $8,000 in silver per ton. By 1859, average grades reached 770 ounces of silver per ton, and the operation was producing an estimated $3,000 per day. Ore was shipped by wagon to Guaymas, Mexico, then by schooner to San Francisco, reportedly paying over 50 percent dividends to investors.

That same year, firearms manufacturer Samuel Colt became the chief stockholder and replaced Heintzelman as company president — one of the more unexpected connections in Arizona mining history.

02The Murders of 1861

The year 1861 brought catastrophe from every direction. Fifteen Mexican and Native American miners were killed when the mine shaft roof collapsed, burying them too deep for rescue. The surviving Mexican workers believed the mine was haunted and fled to Sonora.

Then a foreman known only as "Juanito" was caught fleeing with a load of stolen silver bullion. Poston had him executed as a warning. The silver was never recovered — it was reportedly buried somewhere near the mine, where an estimated $30,000 in silver remains hidden to this day.

Charles Poston left to attend to business elsewhere, placing his brother John Lee Poston in charge. It was a fatal decision. Mexican outlaws, drawn by rumors of Juanito's buried treasure, traveled to the mine, turned the remaining Mexican employees against their supervisors, and tortured and murdered John Poston along with two German miners. All three were buried near the town. John Poston's concrete grave and tombstone are still visible today.

03Apache Raids and Confederate Arizona

The Civil War delivered the final blow. When U.S. Army troops were withdrawn from southern Arizona — including nearby Fort Buchanan — to fight in the east, the region became part of Confederate Arizona, proclaimed by Colonel John R. Baylor on August 1, 1861. With the soldiers gone, Apache leaders Mangas Coloradas and Cochise formed an alliance to drive Americans and Mexicans from their territory, launching escalating raids across southern Arizona.

Cerro Colorado was surrounded by Apache land and under constant threat. By 1864, settlers had erected a walled stone fort on a nearby hill and a guard tower in the town plaza — defensive measures that speak to the desperation of those who remained. Ranchers throughout the Tucson and Tubac corridor abandoned their homes entirely.

The mine operated intermittently through the rest of the nineteenth century and into the early twentieth — the post office ran from April 17, 1879 to April 15, 1911 — but the settlement never regained the scale or ambition of its Poston-era years. Total lifetime production from the Heintzelman Mine amounted to roughly 3,000 tons of ore averaging about 100 ounces of silver per ton with minor gold, lead, and copper.

04What Remains of Cerro Colorado Today

A few adobe buildings survive in the rolling grasslands off Arivaca Road, roughly 55 miles southwest of Tucson. John Poston's grave remains the most poignant landmark — a concrete marker for a man murdered over silver he never stole, at a mine haunted by a treasure that may still be buried nearby.

The site sits on Arizona State Land Trust property, accessible from I-19 via Exit 48. Visitors should check current conditions, as portions of the surrounding area may be restricted. But the landscape itself is much as Poston would have known it: quiet desert foothills, scrub and grass, and the mountains that gave the town its name — Cerro Colorado, the "Red Hill."