Abandoned Towns
Aerial view of brown desert hills cut by a winding wash, with Arivaca Road crossing it and a pale patch at the old mine site

Silver mining town

Cerro Colorado

One of the first American silver mines in Arizona, worked from 1857. Its manager was killed here in 1861, and a story of buried silver has hung over the place ever since. His concrete tomb still sits above ground near the workings.

31°39′32″N 111°16′21″W · ≈3,670 ft

Aerial imagery: USGS The National Map (public domain). See the photographs in the gallery below.

Ruins · 2012 photos

We couldn't confirm who owns the mine site or whether visitors may walk in. The mine's database record lists the land ownership as unknown. The newest first-hand description we found is from 2012, when John Poston's tomb could be seen beside the dirt road near the workings. Treat fences, gates and posted signs as closed, and stay out of old shafts.

Overview

Silver, a killing and a lost hoard

Cerro Colorado sits beside Arivaca Road in the hills about 14 miles west of I-19, below the 4,202-foot peak that gives it its name. Spanish miners had worked silver here long before. In 1856 an Army major, Samuel Heintzelman, located the old mine, and the Sonora Exploring and Mining Company, with Heintzelman as president and Charles Poston among its leaders, began work in 1857. The ore was rich. By 1859 more than 100 men were on the payroll, and bullion went by wagon to Guaymas and on to San Francisco.

Then things went wrong. A cave-in in 1860 or 1861 buried more than a dozen miners, and when the Army left Arizona at the start of the Civil War the camp was on its own. Charles Poston left his brother John in charge. John caught a foreman stealing silver and had him executed. Soon afterward raiders killed John Poston and two German miners and wrecked the works.

The mine came back several times. A post office ran from 1879 to 1911, a new shaft went past 550 feet after 1899, and a small mill worked here in the 1950s and 1960s. Today the reported remains are adobe ruins, the mine workings and John Poston's concrete tomb, which sits above ground because he asked not to be buried in the earth.

Timeline

Eighty years of the Heintzelman

  1. Spanish miners find silver here and work the surface ores, by one account smelting them at Tumacácori.
  2. A boundary survey party notes the old workings. Samuel Heintzelman, an Army major, locates the mine with a Mexican guide.
  3. The Sonora Exploring and Mining Company, with Heintzelman as president and Charles Poston among its leaders, starts mining. A first run of 12 tons of ore yields 2,287 ounces of silver.
  4. More than 100 men are at work, and the main shaft is 70 feet deep.
  5. A cave-in buries 15 or 17 Mexican and Native miners, by different accounts. Their bodies are never recovered, and many Mexican workers leave.
  6. Peak output, with up to 200 workers. The Army pulls its troops out of Arizona as the Civil War begins.
  7. John Poston, Charles's brother and the man left in charge, executes a foreman caught stealing silver. Raiders later kill John Poston and two German miners.
  8. J. Ross Browne sketches the Heintzelman mine and works. A walled stone fort stands on a nearby hill.
  9. A Cerro Colorado post office opens after the mine is reopened.
  10. A new company sinks a shaft to more than 550 feet and works considerable ore.
  11. The post office closes. Mining goes on only off and on until 1937.
  12. A small flotation mill is built. It is removed in the late 1960s, and no major mining follows.
  13. A visitor photographs John Poston's above-ground concrete tomb beside the dirt road near the mine workings.

Legend and record

The foreman's silver

The killing is on the record. John Poston executed his foreman, known only as Juanito, after catching him heading for Sonora with stolen silver, and raiders killed Poston and two German miners soon after. Accounts agree that theft was a constant problem: one estimate is that only about half the silver reached the company.

The treasure is legend. The story goes that Juanito buried his silver, $70,000 worth by one telling, somewhere near the mine, and that the raiders tore the works apart looking for it.

Nobody is known to have found it. We keep the story because it is the reason many people have heard of Cerro Colorado, but there is no record of the hoard itself, and the figure rests on a single retelling.

What's left

Workings, ruins and a tomb

Wikipedia describes a few adobe buildings still standing along with John Poston's concrete grave and tombstone. A summary for the Green Valley Recreation Hiking Club includes 2012 photos of the tomb and marker beside the dirt road near the mine workings. Western Mining History's record, drawn from the USGS database, lists the site as a past producer with land ownership unknown, and like every mine in that database it advises assuming private property. We haven't found a description since 2012.

The historic maps below fill in the setting. The 1920 sheet shows Cerro Colorado with a spring, places named Guadalupe, Madril and San Juan to the south and southeast, and roads running west toward Arivaca. The 1941 sheet marks the Cerro Colorado Mine beside Arivaca Road, with the 4,202-foot peak to the north and the abandoned Colorado Clark Mine to the southwest. The 1979 sheet shows the mine buildings and a tailings patch on Cerro Colorado Wash.

  • Mine workings and shafts
  • Adobe ruins
  • John Poston's above-ground concrete tomb
  • Tailings
  • Colorado Clark Mine, to the southwest
USGS topographic map of the Cerro Colorado mine area with Arivaca Road and Cerro Colorado Wash
USGS The National Map, topo. A building symbol marks the mine site north of Cerro Colorado Wash. Arivaca Road crosses the wash just to the east.
Aerial view of brown desert with a pale patch north of a winding wash and a paved road crossing it
Aerial imagery, same area. The pale patch at center is at the mine site. Arivaca Road runs from lower left to upper right.

Historic maps

Cerro Colorado on USGS maps, 1920–1994

Crops from the USGS Historical Topographic Map Collection, centered on the townsite. Each sheet shows what surveyors mapped that year; compare them with today's topo and aerial on this page.

USGS topographic map around Cerro Colorado, 1920
Arivaca sheet, 1920, 1:125,000 · U.S. Geological Survey, public domain · catalog record

Map & directions

Getting there

Green Valley is the nearest town, and both routes run down I-19 to the Arivaca Road exit and west on paved Arivaca Road. The site is just off the road, about 14 miles in. The routes end on Las Guijas-Cerro Colorado Road a few hundred feet from the mine. We haven't driven them, and we couldn't confirm whether the land beyond the road is open to visitors.

USGS topographic map from Green Valley and I-19 west along Arivaca Road to Cerro Colorado, with the route drawn on it

Base map: USGS The National Map (public domain). Routes: OSRM on © OpenStreetMap contributors data (ODbL), computed October 2026. Times assume dry roads.

From Green Valley24.8 miabout 38 min
  1. From Green Valley, take Calle de Las Casitas and West Continental Road to I-19.0.9 mi
  2. Take I-19 south toward Nogales.8.9 mi
  3. Take the Arivaca Road exit and turn right onto West Arivaca Road.0.5 mi
  4. Follow Arivaca Road west.14.3 mi
  5. Turn right onto Las Guijas-Cerro Colorado Road to the mine site.0.1 mi
Google Maps directionsApple MapsOpenStreetMap

Road and safety notes

  • Arivaca Road has been paved since 1976. The short road into the mine site is unconfirmed; turn back if it gets worse than your vehicle can handle.
  • We couldn't confirm who owns the site, so treat it as private. Don't cross fences or gates, and stay out of shafts and adits.
  • Don't disturb John Poston's tomb.
  • Summer heat is severe. Go in the cooler months and carry water.

Photos

Cerro Colorado in pictures

Visitor reports

Been to Cerro Colorado?

Been there lately? Tell the next visitor what you found: whether you could get in, the state of the road and what's still standing. Photos are welcome. We read every report before it appears here.

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Nearby

Other sites near Cerro Colorado

Straight-line distance from the townsite to other mapped sites in our Arizona index.

Sources

Sources and credits

  1. ghosttowns.com, "Cerro Colorado": fact sheet fields (legal description, climate, best time, remains).
  2. Wikipedia, "Cerro Colorado, Arizona", retrieved October 2026: coordinates and elevation (GNIS 2716), post office dates, the 1861 cave-in, Juanito and the Poston killing, the 1864 fort, current remains.
  3. T. Johnson, "Heintzelman Mine," Green Valley Recreation Hiking Club library (photos 2012), summarizing mining articles including Edgar B. Heylmun's: Spanish mining, Heintzelman and the company, the 1857 first run, workforce and output, the 1860 cave-in, theft, the $70,000 story, the tomb, later shafts, the 1953 mill.
  4. Western Mining History, "Cerro Colorado Mine" (USGS MRDS data): location, elevation, commodities, alternate names, land ownership listed as unknown.
  5. Mary N. Kasulaitis, "Arivaca Yesterdays: M.O. Davidson and the Cerro Colorado Mine," The Connection, 2010: the mine's superintendent in the 1860s.
  6. Jim Forte Postal History, Pima County post offices: Cerro Colorado (1879–1911).
  7. Wikipedia, "Arivaca, Arizona": the paving of Arivaca Road in 1976.
  8. Wikimedia Commons: J. Ross Browne's 1864 drawing from Adventures in the Apache Country (1869) (public domain).
  9. Elevation: USGS 3D Elevation Program point query. Routes: OSRM on OpenStreetMap data, October 2026; not field-checked.

Photo and map credits