Tuesday, August 25, 2020

Goldfield Arizona - A Good Tourist Town.

The Goldfield district lies in the foothills of the Superstition Mountains at the extreme northeastern edge of the Phoenix valley, 5 miles northeast of Apache Junction and 40 miles east of Phoenix. The district extends from Pinal into Maricopa County along the margin of Arizona’s Transition zone within the Basin and Range province. 

Gold was discovered in 1892, and led to construction of Goldfield boomtown. The town was occupied by more than 1,500 residents with a post office established on October 7, 1893. The rush was short-lived. By 1897, many mines lost their glitter, and miners packed up and left Goldfield to the ghosts. 

But the ghosts were again haunted by miners and prospectors when a second community was established at the original townsite, and renamed Youngsberg. Mines re-opened, and a mill and cyanide plant built to recover gold, and a Post Office established on March 15, 1920, two years after the end of the first world war. 

But the mines again lost their attraction and the town was vacated in 1926, leaving it in the hands of ghosts. Today, the town has been revived by tourist trade and the town stands once again with both the living and the dead. The tourist attraction, a replica of the old mining town, provides exhibits of old mines, a brothel, saloon, museum, livery, gift shops, galleries, gold panning and more. You can even take a mine tour and sometimes see a gunfight. It is a highly recommended stop when visiting the Phoenix east valley, whether you are sentient or ghost.

Goldfield is accessed from Route-88 (North Apache Trail). Along the way, you will drive by the Superstition Mountains Museum. This is a highly recommended stop with old stamp mills, and information on the Lost Dutchman mine. After your museum tour, Goldfield is just another 0.8-mile up the road on the left. The Goldfield 7.5-minute quadrangle encloses much of the district and shows locations of some mines and prospects.

Wilson and others (1967) report that the district is covered by a pediment surface overlying coarse-grained granite, granite breccia, granite pegmatite and indurated (hardened) arkosic conglomerate. The principal mines in the district lie along north-trending, (west-dipping) shear zones (faults). 

The most productive mineralized zone at Goldfield was known as the ‘Mormon stope’ mostly mined out prior to 1898 at the Mammoth mine, north of the town. A stope was developed on an ore shoot, discovered north of the main Mammoth shaft at an intersection of a cross-fault with a shear zone, which provided permeability favorable for gold to flood the structure. The caved portion of the stope is 100-feet by 25-feet where granite is stained by limonite with irregular stringers of coarse-grained, white, quartz. Limonite (some gold-bearing) is likely derived from pyrite oxidation.

The district is best known for sporadic, fault-controlled, rich, ore shoots in large blocks of low-grade gold ore. During its heyday (1893 to 1898), the Mammoth, Bull Dog, and Black Queen mines produced about 60,000 ounces of gold and 20,000 ounces of silver. You can find out the value in present day's dollars by using links on Searching for Gold

There are no known reports of placer gold in the district other than a passing statement by Dinsmore (1911) stating that within a 3 by 8 mile area, “gold may be panned anywhere”. A sediment-filled arroyo crosses the mineralized structure to the north and west of Goldfield, and likely has some gold. Based on some of the reported high-grade zones in the faults, it is likely a few nuggets and gold dust lie buried in sand and banks of the arroyo (search Google Earth for ‘Goldfield, AZ’). Like most stream beds in the desert, it is rare to see standing water in this drainage except after rare downpours. Since the drainage receives runoff from the nearby Goldfield Mountains, flash floods are not uncommon. 

Gold was discovered in this area following a flash flood that exposed granite porphyry breccia containing visible gold. The granite was covered by arkosic conglomerate before it was exposed by the flood waters (arkose is a sedimentary rock with considerable quartz and feldspar and of similar composition as granite). Prospectors reported some very old mine workings were found in the area, indicating gold had been sought by unknown miners prior to 1892. 

The principal mines are the Black Queen, Bulldog, Mammoth and the Old Wasp; however, other mines and prospects were dug including the Bluebird, Doc Palmer, Copper Crown, Tom Thumb, Fairstake, Treasure Vault, Golden Hillside, Highflyer, Lazy Doc, Goldstake and Gold Bond. These are described by Hausel (2020).