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Denn Mine, Bisbee Arizona

Last Updated: 28th Jun 2017

By Rolf Luetcke

Denn Mine, Bisbee Arizona
By Rolf Luetcke

The Denn Mine started up known as the Denn Shaft in 1907 and, over time, went to a depth of 3157 feet. Early on the Denn was also known as the Robert E. Lee Claim. At that time it was started by the Denn and Arizona Copper Company which later became part of the Shattuck Denn Company. It was named after Maurice Denn who with Lem Shattuck and Joseph Muheim owned 13 claims in the area. The mine had a lot of problems with water and was flooded more than once. In 1920 the mine was flooded completely halting operations and because of low metal prices the mine was not worked for five years when it was again started up and ran continuously until 1944. The mine was sold to the Phelps Dodge company in 1947and mined for ore to the 3100 foot level. The Denn Mine produced a lot of copper, silver, lead and zinc ores but one sees few specimens from this mine.
My connection to the Denn is not from any minerals that came from the mine but from Richard Graeme who at one time in the 1970's ran a small mineral distribution effort for the Phelps Dodge Company from a shack by the old Denn Mine. When I lived in Bisbee Richard had told me of the shack and his few years selling minerals for the Phelps Dodge Company from there. He said workers at the mine had brought over loads of ores from the Holbrook Extension and deposited them outside of the small building. The exploratory drilling for the Holbrook Extension that had been done from the 400 level of the Gardner and Holbrook mines as well as from the surface and other areas. This work showed good specimen grade material that would be encountered during the upcoming mining and the Phelps Dodge Company wanted to save as much of the better material as possible. Since I was making mineral specimen collections Richard thought I might be able to use some of the material that was lying about near the old building. That mine was under Phelps Dodge control but no work was being done on that side of Bisbee. He said I could probably drive by on a Sunday and pick up some of the material to use.
Richard was the one in charge of this project from the fall of 1969 until 1973. The Denn location offered a secure location to bring the specimens and had the space to work with them. Richard told me thousands of specimens were recovered from the Holbrook Extension mine operation and he said probably thousands more specimens were taken home by the people who were doing the mining. The Phelps Dodge company was very generous in allowing this recovery of specimens by the miners which allowed for thousands of Bisbee mineral specimens that made it out to museums and collectors worldwide. Richard told me that the saving of mineral specimens went back to the 1880's by Phelps Dodge and they had always had a very progressive view of saving fine mineral specimens.
The main mineral that was found in the Holbrook Extension effort was malachite, sometimes in large specimens over 200 pounds. I remember seeing a number of these specimens over the years. Much of the material was cutting grade material and was often worked into jewelry. The Bisbee malachite had chatoyance, which is a reflective quality of the crystal structure that made for a play of light like you see in tiger eye. I have myself worked quite a bit of this material over the years. A funny story comes to mind with the malachite from Bisbee. A fellow came into our business at one time and saw I was cutting malachite and he warned me that I had to use a mask while working this material since it could give one arsenic poisoning if you breathed the dust. I had to laugh and told him that was not possible but he insisted so I let things go. I know the copper dust is not good and one could get copper poisoning if inhaling too much of the dust but my efforts to explain that it had no arsenic in the formula went right past the fellow.
Besides the massive malachite there was boxwork malachite in large pieces with the spaces having azurite spheres, making for beautiful specimens. These were found from small size to pieces over 1500 pounds. There was also cuprite found in huge masses, some over ten tons in size. I had often thought that many of the rare minerals from Bisbee could be found in this material but from Richards contact he said these huge masses rarely contained the rare species. There were small open pockets that did contain bright cuprite crystals but most were tiny crystals. I have a few of these in our collection and they are very pretty specimens. There is a collecting story by the miners that comes to mind with the huge cuprite boulders. Jack Hanley, who worked on the repair crew that fixed problems the equipment might have. He was on a call to the back of the Lavender Pit one day when he saw a huge piece of rock lying by the road that had not been there before. After the repair he stopped on the way back to the shop and took out a hammer from his truck and broke off a chunk of the big boulder. When he picked it up he saw it was cuprite. He took the chunk he had removed back to the workshop and showed it to his fellow workers. He told them it was by the back of the Lavender Pit. Jack took his piece home after his shift and didn't think anything about it until the next morning.
The next day the bosses called everyone in for a conference. It seems that the shovel operator had found one of the ten ton plus cuprite boulders talked about above and had brought it to a wide spot in the road for the company to pick up to use as a show piece in one of the office buildings in Phoenix. They had said if a big boulder was found to lay it aside for the company to use. The next day they had come to get the boulder but couldn't find it. When then checked around they found out what had happened. When Jack had shown the piece to the workers and the shop they had driven their trucks up after their shift was over and with big hammers had broken up the piece and hauled it home. Not knowing it had been placed there for the company to use they had all gotten into big trouble and it had put an end to the free and easy collecting that had been the policy before this incident. Jack had no idea that his breaking off that small piece had started a chain reaction that had bigger consequences in the end. The policy of picking up specimens came to a halt for Jack and the other fellows who had broken up the boulder with being told if they were caught with specimens they would be fired. This was a reaction to the loss of the cuprite but that relaxed again with time and Jack said he did take home other things after that. One time he was found holding a piece of turquoise he had just found on one of his rounds and a boss stopped by just at that time. He was told to break the piece in half and when the boss looked at the two pieces, he handed Jack the lesser piece and said "don't let me catch you again!" I guess the strict policy had again relaxed a bit.
Chalcoalumite, a type locality mineral from Bisbee was found in this area. Much of it was in blue coatings on the host rock but some was in hard goethite matrix and this often had wonderful tiny twinned crystals. From the material I found at the Denn Mine location I found quite a few nice specimens of this material. It all came from this Holbrook Extension operation.
Richard told me that native copper was also abundant here but mostly unimpressive as specimens. The copper could be found in pieces of several pounds. In the collection of material I purchased in Mexico from Senor Castellanos there was quite a bit of this copper. None of it was impressive and little had crystals. The miners who worked on this project often took their take home pieces to Castellanos to sell for a bit of extra money.
Richard told me that during the mining of the Holbrook Extension the mining often would stop for several days to allow for the recovery of specimens, which were taken to the Denn Mine location. Richard said the recovery efforts didn't earn the Phelps Dodge company any money but they were trying to save the material for posterity. Some was lost to the mining during this time since not all could be saved but much did survive. Richard told me also that the few years of saving of specimens allowed him a great opportunity to study and understand the geology of how the deposit formed. There were large pieces of the hard, black goethite matrix material and in some of those they had found large and very bright azurite crystals. My piece with the three bright crystals came from this same material. Since the hard matrix often had completely surrounded azurite and malachite I later found it made for nice cutting material. The material was some of the dirtiest material while cutting and grinding but the finished product was quite pretty.
Since I was making mineral specimen collections in the mid 1970's, it was after the Denn Mine operation had ended. Richard told me one time that I could drive over there to see what was still there and I did just that on several trips to the place and one of the pieces I found was a hundred and twenty pound piece of solid cuprite. The piece rang like a gong when I hit it with the handle of my hammer. I kept that piece as a whole piece and stored it away for later. Unfortunately I lost that piece as part of a divorce settlement and never did find out what ever happened to it. Richard told me that it was not a great loss since those pieces rarely contained rare minerals and it made me feel a lot better. I had always envisioned great pockets in the piece with connellite or other species but his assurance made me feel better about losing that piece.
Richard had some large chunks of the black goethite that contained azurite brought in and I took a few of those. One piece I had brought home I broke up and found one pocket of azurite crystals that was the nicest grouping of crystals I had come across. Just as I had found the piece on my porch, my neighbor, Ernest Zavala came home from his shift underground at the mine. He saw me looking intently at something and asked what I had found. Since Ernest worked at the mine and had often brought home a thing or two from underground I assumed he knew how to handle a mineral specimen. The pocket I had opened had three elongated and perfect long, blue azurite crystals sticking up nicely from the hole. The crystals were perfect and I was just thinking how it was the nicest azurite I had in my collection when Ernest asked if he could see the piece. Not thinking anything about it I handed him the piece to look at. Since my porch was in the shade he asked if he could look at it in the sun. I said sure and we walked to the sun and he held the piece up to look and see if the crystals let light through. Then something happened I had never anticipated. Ernest reached up with his other hand and with his thumb he raked it across the three crystals and all three snapped off at the base.
I stood in silence, trying to think of what to say. Ernest handed the piece back to me saying "kind of brittle, aren't they". I couldn't find any words and all kinds of thoughts went through my mind but I realized something I never forgot, people have different ways of thinking about minerals. Although Ernest worked at the mine and had brought home turquoise and other things, he was not a mineral collector and looked at minerals in a whole different way. He didn't break the crystals in any kind of attempt to ruin them but only looked at minerals from a utilitarian way. He had not thought of value of any pieces or how much they may mean to someone else but had only wondered how tough the crystal were. He had no idea he had just ruined my best piece. I knew Ernest well and knew he didn't have a mean bone in his body and had not realized at all what he had done. I decided not to say anything to him and he went on his way home.
What I learned from that one experience was that to always be careful when letting anyone hold a valuable specimen. Something like this never happened again but I still mourn the loss of that wonderful little specimen.
There was one material that Richard had at the small open area by the building and that was the host rock that held the type locality mineral chalcoalumite from Bisbee, which was discovered and described in 1925. I was able to find quite a few great specimens of this mineral from the rocks near the Denn mine building. From the finds made during this time they saw the first nicely crystalized specimens of chalcoalumite. I have some of the earlier material that is more a light blue coating and had not seen nice crystals until I brought home some of the material from near the Denn Mine. Most of the other material from there was ore and wasn't in show case specimens but mostly micro material when broken down.
I was grateful for Richard telling me about this spot and the few trips I took to get material from his piles. I know there must have been other wonderful things lying about but since it was not entirely legal for me to go and pick up things there I didn't press my luck or his generosity in telling me about it. That was at a time when the Phelps Dodge company was not too strict about people picking up specimens and since I lived in Bisbee and often drove the back streets to explore, there were no signs to keep out at the area I had been in. In later years these areas were blocked to regular traffic and the area was no longer open for anyone to drive in.
This is one small story of Bisbee I thought people might enjoy. I assume there are people who have visited the Denn Mine to purchase specimens between 1969 and 1973. After I left Bisbee in 1986 I never had an opportunity to visit the Denn Mine again and I am sure it is no longer open to access.

Article has been viewed at least 975 times.


Rolf, Nice to hear about some of the "heyday" times of mineral specimens! David K Joyce

David K. Joyce
3rd Jul 2017 1:47pm
Nice article Rolf-your history is always accurate and is an enjoyment to read and take us back in time. Thank you for sharing your many experiences with members of Mindat.

Brander Robinson
4th Jul 2017 11:11pm

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