Many stories about abandoned mines in Arizona don’t have happy endings. For example, the Tonopah-Belmont Mine, located about 24 miles southwest of Wickenburg, operated intermittently from the 1860’s until 1942 with a record of no fatalities. This, in spite of having a 500 foot deep shaft with working levels at 100, 250, 400 and 500 feet.
Responsible collectors of mineral specimens regularly (and safely) visited this popular site for 48 years until, in 1990, a young man set out to explore the underground workings on his own. About 100 feet into the McNeil Tunnel, in darkness, he stepped into a winze and fell 350 feet to his death. The entrance was sealed off a few years later but, in June 2002, another visitor entered the same tunnel after prying open the protective metal grating. Predictably, his fate was identical to that of the previous victim. The Tonopah-Belmont Mine now has the distinction of having more fatalities in its underground workings after it closed than during its long years of operation.
Arguments for or against mine closures can be passionate – if not always rational. At one extreme, some would advocate that all underground mines should be found and permanently sealed – regardless of the cost for closing an estimated 100,000 shafts and adits in Arizona. At the other extreme, some argue this is simply wasteful government spending, that public funds should not be used to remediate any mine opening unless it is leaking toxic substances into the water table or poses a similar ecological threat.
To be sure, injuries, fatalities, vandalism and ecosystem damage have left an unhappy legacy at more than a few of Arizona’s historic mines. Federal and State agencies have struggled to find solutions but, as off road recreational vehicles make more mines accessible to incautious people, there is an increasing sense of urgency to destructively close mine entrances; either by collapsing the entrance with explosives or by backfilling with rock and soil. Some official circles have even suggested dumping old tires into abandoned shafts.
An example of destructive closure can be found at the Mammoth Spar Mine south of Wickenburg, between Vulture Peak and Morristown. In January 2010, the BLM contracted to have five shafts backfilled with waste rock from the mine dump. The Mammoth Spar was an underground fluorspar (calcium fluoride) mine that dates to the early 1950’s. Records indicate the mine produced about 100 tons of the mineral, which is an important flux material for smelting. The shafts at the Mammoth Spar are not particularly deep, ranging from 60 to 100 feet to reach the mineral vein. The area within a one mile radius is dotted with old shafts and adits, many of which are within a few yards of old mine trails.
Figure 1 shows the location of the Mammoth Spar Mine, including five shafts that were backfilled. The two with red arrows were photographed by me. A sixth shaft was also backfilled at another location about 1.5 miles west of Vulture Mine Road near the upper end of Mill Wash. This shaft is not related to the Mammoth Spar Mine.
Figure 2 shows the results of backfilling at the south shaft shown on the map. The second (red arrow) shaft is about 200 feet to the left (north) of this photo.
At first glance you might think the area was scraped clean, that historic artifacts might have ended up in the bottom of the shaft; but that is not the case. The decision to seal, fence or gate a mine entrance involves a careful, sometimes lengthy, process that includes inspections by mine engineers, archaeologists, wildlife conservation personnel and mitigation experts. Items of historic importance, even old concrete foundations, are left in place. Trash dumps that contain old cans and bottles are not disturbed and, generally speaking, are not located on the mine dump or tailing pile anyway. The appearance of the shaft area in Figure 2 shows that waste material from the mine dump was used for fill and leveling purposes. According to the BLM, nothing else at this site was moved or destroyed.
Surprisingly, there is a recently fenced open shaft less than 100 feet from Figure 2. This shaft is as visible, accessible and dangerous as the five nearby shafts that were backfilled. In fact, it was so dangerous that wildlife specialists could not safely rappel into it to perform subterranean inspections. The Arizona Game and Fish Department will conduct “emergence surveys” later this year to determine if bats or owls are flying in and out. This type of survey, typically using night vision or motion activated cameras, is not totally effective in determining seasonal use or the size of a resident colony, but it is one of few alternatives when safety is an issue. Only after this survey is completed will a decision be rendered on the final disposition of the shaft. In the meantime, the fence serves as a visual warning to visitors.
Since it is impossible to fall into a hole that doesn’t exist, you can say that destructive closure is 100 percent effective. Still, there is something vaguely disturbing – a sense of history lost – about closing an old mine site in this manner.
In Part two we will examine an alternative known as “Protective Closure” that preserves subterranean mine workings for wildlife while preventing access to people.
Footnotes and References:
 Steve Voynick. “Stay Out and Stay Alive.” Rock & Gem, July 2006.
 Arizona Daily Star, “Plan: Use old tires to plug state’s abandoned mines.” February 1, 2010. The State Mine Inspector’s Office advocates dumping tires into shafts because they are cheaper to haul than concrete, gravel or bricks. The state has a problem figuring out what to do with a growing surplus of waste tires.
 Funding was provided via the American Recovery and Reinvestment Act (the federal “stimulus” program) and cost $14,300.
 The main site of Mammoth Spar Mine is located at N33 52.763′ X W112 43.118′ in the NW1/4 of section 7 T6N, R4W. Mindat erroneously places the mine in section 5.
 “Managing Abandoned Mines for Bats.” Scott Altenback, University of New Mexico; Richard E. Sherwin, Christopher Newport University; David L. Waldien, Bat Conservation International. External surveys (such as above ground motion detection) are only 61 percent effective in confirming the presence of a bat colony inside a mine.
 There is no record of injury or fatality occurring at any of the abandoned shafts that were backfilled. Although there were several complaints filed by recreational visitors to this site in the past, the BLM’s policy is to proactively close abandoned mines that may pose a risk of injury or death.
Last 5 posts by Allan Hall
- Wickenburg Hospitality Comes in Many Forms - December 15th, 2010
- Calliandra Eriophylla is Native to the Wickenburg Area - December 9th, 2010
- Goodbye, Old Bridge - November 29th, 2010
- Abandoned Mines Part III: Preserving the "Whispering Ranch" Mine - March 25th, 2010
- Abandoned Mines Part II: Protective Closures - March 10th, 2010