I’m new to Arizona. I’ve grown up in and lived most of my life in Canada. That means the desert landscapes, flora, fauna and types of minerals (secondary minerals) of the South-West are all new to me! I’ve travelled much of the world but Arizona is one of THE most interesting, intriguing and satisfying environments that I have encountered (especially during winter and spring!).
Recently, I joined a field trip of the Tucson Gem and Mineral Society, destination; the Red Cloud Mine, north and east of Yuma, not far from the California and Arizona border. I left Tucson and travelled NW on I-10 to Highway 8 and then west on Highway 8 to Yuma for a stay overnight and ready to start early the next morning, heading up highway 95 towards the mine.
I had NO idea what collecting would be like. Actually, I didn’t care. It just seemed like a good idea to visit the Red Cloud Mine which is one of the premier mineral localities of the world. This year, 2019, was the year of the “Wulfenite is Loved” theme at the Tucson Gem and Mineral Show and visions of colourful, well-formed crystals of the AZ-ikonish, lead-molybdate were floating around in my brain. The trip to the mine was important and, if I happened to find some good crystals, that would be a bonus!
I think that I enjoyed the drive from Tucson to Yuma and then to the Red Cloud Mine just about as much as I enjoyed being AT the Red Cloud Mine! This “article” is really a photo-essay showing the road trip to the Red Cloud Mine, a little about the location, collecting and then some of the minerals that I returned with. I’ll show you some of the scenery, flora and minerals that I encountered. Didn’t encounter any fauna! I hope you enjoy it, as well!
About the Red Cloud Mine
The following information has been summarized from Arizona Lead and Zinc Deposits, Part II, Arizona Bureau of Mines, Geological Series No. 19, Bulletin # 158, kindly provided to me by Les Presmyk, an authority on the Red Cloud Mine and "all things Arizona", when it comes to mineral specimens. I’ve added my observations to the information gleaned from the reference.
The Red Cloud Mine was a fairly small mine, as modern mines go. It is located at 750 feet above sea level, near Yuma and the California border with Arizona. It was originally mined during the 1880s and over the years, developed to a depth of 500 feet or so via various shafts, winzes, raises, drifts and stopes. The remnant vein mineralization in the 1950s averaged about 6% lead and 10 troy ounces or so of silver per ton. There were no doubt higher grade sections of the veins, earlier, but few records are available.
The vein occurs in a fault zone and is composed mainly of “limonite”, hematite, quartz, fluorite and calcite. According to the Arizona Bureau of Mines (ABOM) report, there is considerable fault gouge and brecciated rock around the vein. I observed this in the surface exposure of the vein and expect that the underground workings were tricky due to difficult ground conditions. There are many open spaces in the vein material and the openings are often drusy quartz lined. When not filled with iron and manganese oxides the openings commonly contain fillings or crystals of wulfenite, willemite, cerussite, mimetite and calcite. According to the ABOM report, there also can be malachite, vanadinite, smithsonite. Small masses of galena can be found and, presumably in large masses, at times since argentiferous galena was the main ore mineral. Also according to the ABOM report, the galena can be associated with anglesite, cerussite and cerargyrite. As well, the report indicates that the lower workings contained more zinc mineralization than lead, all in secondary minerals. Odd, though. I didn’t see a trace of zinc mineralization during my limited visit.
I was surprised at the number of open spaces in the vein material and the quantity of small crystals of wulfenite, willemite, cerussite, mimetite and hemimorphite. I recognize that I was looking through vein material both in-situ and loose that is the “leavings” of several waves of professional collectors. Still, there are beautiful, small but macro wulfenite crystals to be found and oodles of micro crystals. Roger the resident collector, mentioned further, below, has found some beautiful large and significant crystals and specimens of wulfenite. He spends many hours exploring the workings and has learned where to look. He was very generous with his knowledge and guidance but we were probably not shown the best place to collect on surface and certainly we did not go underground. (I would have loved to!)
Results of Collecting
I was fortunate to find a number of wulfenite crystals, all small but, still, beautiful and classic Red Cloud Mine. They all have that red-orange colouration, sometimes more red and sometimes more orangey. As well, I also found lots of really nice willemite, all sharp micro crystals and all brilliantly fluorescent.
As well, I did find cavities of fluorite crystals. The fluorite crystals are not great crystals and mostly colourless but often serve as substrate for the more exotic minerals. The fluorite has nicely blue-purple fluorescence and adds to the intrigue of the rich willemite specimens. Similarly, there are lots of vugs lined with drusy quartz crystals that sparkle in the strong, ever-present Arizona sun. The quartz druses are often the base for the more rare minerals.
Additionally. I did find a couple of vugs with hemimorphite, mimetite and cerussite crystals. I expect that, if I spent more time at the mine and with the microscope, I’d find other well-formed crystals of various minerals.
Here are some photos of the minerals that I found:
ALL of the Willemite fluoresces a bright green colour like in Figure 46. For some reason, I could not capture that colour through the microscope. All of the micro Willemite photos show the mineral with a ghostly whitish glow.
Here are some REAL wulfenite crystals and specimens:
I was delighted to visit the Red Cloud Mine after knowing about it all of my life and after having sold a number of nice specimens over the years. Hopefully, I’ll return there sometime in the future and undertake another attempt to find a larger cavity with some larger, beautiful crystals in it than I found the first time! In the meantime, I hope that you enjoyed the trip to the Red Cloud Mine as much as I did.
Thanks to Roger, at the Red Cloud Mine, for his guidance during the visit. I hope that he continues to find great crystals.
Thank you to Les Presmyk for the knowledge that he shared about the mine.
And thank you to Ray McDougall for the use of his photographs.