Grand Central Mill

Today all that remains of the Grand Central Mill are the foundations of the six levels stretching up the hill side.

Silver ore was found near Goose Flats by prospector Ed Schiefflin in 1877. Other prospectors soon followed filing their own claims. As other miners and companies flooded into the area, the camp was moved onto Goose Flats and named Tombstone.

The amount of ore was so abundant that the owners had to just sack the ore and stack it up until it could be processed. The problem was there wasn’t enough water at Tombstone for a mill. Between 1879 and 1882, 6 stamping Mills were built along the San Pedro River some 8 to 10 miles from Tombstone to process the ore. One of these was the Grand Central Mill near the future town of Fairbank which was established when the railroad arrived in 1882.

The Grand Central Mill was completed in December of 1880 and started processing ore from the Grand Central Mine in Tombstone at Christmas time. The size of the building was 200 ft. by 130 ft. It was 90 ft. from the upper level to the bottom level. There were six levels inside the mill. This mill with 30 Stamps was the largest and most efficient mill to be built along the San Pedro. The Stamps were set up in banks of 5 stamps in each mortar box. The Mortar boxes were fed from a 150-ton ore bin.

A single stamp was a rod of steel about 14 ft long and about three inches in diameter with an iron shoe (8.5 inches in diameter by 7 inches tall and weighing 800 lbs.) attached to the lower end of that rod. Total weight of each stamp was between 2,500 and 3,000 lbs. At the top of the stamp there was a collar that was engaged by a pawl connected to a cam shaft. The cam shaft was turned by a belt driven by a steam engine. This cam shaft allowed a pawl to lift each stamp and gravity pulled the stamp back down.

Each stamp was lifted and dropped approximately 50 times per minute. This crushed the ore to a powder. In the wet milling process, as in the Grand Central Mill, a small amount of water was introduced into the mortar box at the bottom of each bank of stamps producing a sort of slurry.

The resulting slurry was then mixed with more water in a series of water tanks and Quicksilver (Mercury) to form a type of paste. The silver would adhere to the mercury. After settling and straining in additional tanks, the amalgam was heated to boil off the water and Mercury leaving silver and traces of other metals (gold, copper, zinc and lead).

Sometimes these mills were called reduction mills because the ore volume was reduced to a product that could be transported more easily, usually a bar 4 inches by 4 inches by 4 feet long weighing 180 pounds. These bars were then taken to a large smelter to further separate the various metal elements.

The Grand Central Mill was in operation from 1880 to 1889. When the mill closed for good in the spring of 1889 and was dismantled, some of the equipment (5 railcar loads) was sold to the Oso Negro Mine in Sonora, Mexico. In the summer of 1905, 20 of the remaining stamps were moved to the Girard Mill in Tombstone during a renovation to that mill. This made the Girard Mill a 40-stamp mill. Today all that remains of the Grand Central Mill are the foundations of the six levels stretching up the hill side.

The ruins today can be visited by taking the trail north from the Fairbank Townsite. The townsite is located about 10 miles west of Tombstone on state Highway 82. The distance is about 1.4 miles along a very well-maintained trail that is relatively flat and shaded in places. The townsite visitor center and museum is in the old Fairbank School House and is operated by The Friends of the San Pedro River.

The visitor center is open Friday, Saturday and Sunday from 9:30 a.m. until 4:30 p.m. with the townsite itself open from sun up until sun down daily. All of the old mill sites along the river are in the San Pedro Riparian National Conservation Area, administered by the Bureau of Land Management. The Friends of the San Pedro conduct guided walking tours throughout the year to several of these sites. Dates and times can be found on the Friends of the San Pedro River web site at

Merle Kilpatrick is a docent with the Friends of the San Pedro River. He is also a retired Navy Officer and retired school teacher/coach and also volunteers at Coronado National Memorial. He can be reached at or FSPR, 9800 E Highway 90, Sierra Vista, AZ. 85635, phone (520) 459-2555. See our website at for our schedule of events. Like us on Facebook!