Magma Copper Company

  A perspective on a decommissioned mine

Historical Report 20200818

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The Experience

Back in the "stone age" I used to work in an underground mine.  Not by choice, mind you, but the pay was too good to pass up.  Being in college at the time, money was in short supply and I already had a job working as an EMT at a local ambulance company.  Despite requiring skills and certifications, the pay was, well, shit.  It did, however, offer the ability to work around my class schedule, and sometimes I even got to study and/or sleep on the job.  But, lots of hours for little pay, schedule flexibility notwithstanding. 

One of the local copper mines came to the engineering college at the University of Arizona looking for part-time employees from the engineering student body.  The pay was 3 times what I was getting for doing manual labor.  The deal was 2+ shifts a week and because I needed the cash, I did both the ambulance and the mine, with the inevitable impact on my physical and mental well-being.  But, at least I could buy beer.  In total, I worked there for a couple of years in two capacities.  The first gig was on the track maintenance crew and the second as a production "chute tapper".  Track maintenance usually involved repairing rails that had been damaged during a derailment and the second involved swinging a 15 lb sledge hammer known as a "double jack".  Both were hard, dirty, thankless work and neither were fun.  But it did pay well.

The mine was known to the locals as "San Manuel" for the nearby village.  Formally it was Magma Copper Company, San Manuel Division.  Unlike most of the other copper mines in this area of southern Arizona which are "open pit", this mine was underground, also known as a "hard-rock mine".  One of my good friends from college also worked there at the mine, as did his father, and they obtained an informational brochure on the mine.  Those pages are scanned and included below.

The mine used a technique called block caving where the ore body was undercut and pulled out from below.  The ground subsequently collapsed into the hole, with cactus, trees and other vegetation coming along for the ride.  The result was a huge, ugly scar and steep, dangerous cliffs.  The mining was done well below the local water table and without any other actions, the mine would fill with water.  During normal operations, water was pumped from the lowest levels of the mine and discharged at ground level.  Eventually, the mining operations depleted the ground water causing a ruckus with the local ranchers.  Mining is big business in Arizona, so you can guess how that story ended.  Magma also ran a smelter in the San Pedro river valley a few miles from the mine.  The smelter produced plenty of sulphur-based noxious gasses which eventually killed a large number of a sahauro cactus in the valley.  In 2003 after an acquisition, the mine was permanently closed.  Above ground equipment for the mine and the smelter was sold and eventually relocated to Chile.  For additional information on the mine, see Wikipedia.
  After the mine was closed, the tunnels and shafts flooded with ground water and the site was abandoned.

The mine had its own concrete plant for use in underground reinforcement of the tunnels.  Concrete was manufactured on the surface and then dropped down special pipe and re-mixed at the destination level of the mine.  The concrete management techniques are described below.

When I worked there, the mine had 6 levels: 2015
(feet below the "collar" at the surface), 2075, 2315 , 2375, 2615, and 2675.  Note that to get to the work area, you had to descend in the "cage" almost half a mile.  The deepest shaft descends to a depth of 3680 feet.  I worked on each of these levels at one time or another and the lower levels are hot-as-hell and very humid. 

In the end, only about half of the available ore was recovered.   The ore body was split by a vertical fault so the upper body was mined first.  The second part was overcome by a combination of environmental and financial issues and remains in place today.

The photos below are scanned from the informational brochure, complete with coffee stains and creases.  The publication date of this material was not stated in the document.  Enjoy.

This photo must have been taken early during the mine's operation.  Note the subsidence zone in the left-of-center area of the photo above.  The production headframes used to hoist ore-bearing muck to the surface are at the upper left.


Magma produced lots and lots of ore over the years and employed many local miners and support personnel.  In the end, the mine was purchased by BHP and then shut down.  The surface structures were dismantled and sold or scrapped.  The smelter was dismantled, the smoke stacks were dynamited and the area reclaimed.  My cousin Jim was part of the reclamation and restoration effort and was on-site when the smelter stacks were blown, see photos below.

And just like that, an era came to a close.

In addition to the still photos, Jim also captured video, see this link for the video of the stack collapse.

A variety of Youtube videos are available on Magma including the "definitive history" by Onofre Tafoya, one of the old timers.  See this link for more videos.

Working at the mine was hot, dirty, dangerous, thankless work that paid the bills.  I had a number of close calls there, but was never seriously hurt.  That said, I am glad that I became an engineer and never had to work underground again.  I did return to the mine, but as part of a tour run by a school classmate that worked there.  It was an exciting tour, but brought back some unpleasant memories.

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