This article appeared in the March 1998 issue of Rock & Gem Magazine
Some of my favorite places to collect mineral specimens are near Wickenburg, Arizona, which is about 50 miles northwest of Phoenix. The mountains around Wickenburg have been extensively mined for (gold, silver, lead and copper, so it is common to see old mining roads, tailings piles and adits everywhere you go. One of the prominent geologic features of these mountains is a major system of parallel faults (middle Tertiary in age) which trend north to northwest and dip 30 to 50 degrees to the southwest. Many of the mining prospects in the area (including the Purple Passion Mine) are located in these faults, which tend to be filled primarily with ore-bearing quartz or calcite.
In these mountains, the desert climate is a little milder than in the lower desert, but in the summer months, daytime temperatures still climb above 110 degrees Fahrenheit and winter temperatures dip below freezing on some nights. This portion of Arizona is considered a high desert (it only gets about 6 inches of rain per year), but it is not composed of barren sand dunes there are many plants and animals. Most of the large plants like cacti, mesquite trees, palo verde trees, willow trees and creosote bushes tend to encroach on the roads. As you drive through them, your vehicle's mirrors and paint job will take a beating, (I affectionately refer to the resulting scratches as Arizona pin-striping).
Large tracts of land around Wickenburg are controlled by the Bureau of Land Management (BLM), and the land is leased out for cattle-grazing. Wild animals and range cattle are apt to be anywhere. You especially need to keep a sharp eye out for the range cattle. Many times we have encountered herds of them hogging the road. They usually don't get out of the way, but rather seem to take great delight in stampeding right down the road in front of you for thousands of feet. They often stop when you do, but still don't move to the side. If you manage to get past the cattle and are lucky, you might catch a glimpse of a deer, coyote, javelina, fox, mountain lion, jack rabbit or other large wild animals. We have seen all of these animals except for a mountain lion. If I see one of these, I hope I'm in my vehicle at the time. Sometimes the deer are especially hard to see because they blend in so well. One time when I was leading the way for another car full of collectors, I stopped the truck to point out some old concrete foundations at an abandoned mill site. Later, I found out I had completely missed seeing the big doe walking up the hill next to the foundations (at the time, I had wondered why they were taking so long to look at lumps of concrete).
The mineral collecting throughout the entire area is excellent. On the way out of Wickenburg, heading north on Constellation Road, close to where the blacktop ends and the dirt road starts, you find small geodes filled with little quartz crystals, which fluoresce a bright green. Amethyst Hill is a few miles farther north, and with some hard work, good specimens can be found with crystals about 1/2 inch long that have alternating bands of smoky quartz and amethyst. Leaving Constellation Road and traveling about five or six miles to the east, you arrive at the Monarch Mine, where pale blue and green fluorite octahedrons up to 2 inches can be found in the tailings. These tailings also have quartz crystals, chalcopyrite and some wonderful needleshaped (acicular) crystals of malachite. Of all of the collecting places in the area, my favorite one is the Purple Passion Mine. This mine produces some awesome fluorescent mineral specimens for night collecting and it also has some very odd wulfenite crystals and a variety of other minerals to collect during the day. It got it's current name because of the purple fluorite matrix that occurs at the area where the newest shaft has been driven.
I first became interested in this mine about two years ago, when I saw an unusual specimen at the Rockazona rock show in Buckeye, Arizona. This specimen had 1/4-inch yellow-orange wulfenite crystals in a matrix of fine-grained purple fluorite. Now, I'm not a sports fan, but even I can recognize the potential of specimens with the colors of the Phoenix Suns. An inquiry at the table determined that the owner of the piece was looking for some partners to help open up the site.
The Purple Passion Mine can be reached by driving out Constellation Road about four miles to the north and then another four miles to the east into the desert. On the way to the mine, you pass through a cattle gate, go through several arroyos that are connected by stretches of old mining roads, and you encounter a windmill pumping water to a tank and a cattle trough. During rare flash floods, these arroyos can be quite treacherous; if there is water in one, do not try to drive into it. At the mine site, there is another cattle stockade, which is watered by a windmill.
On a recent overnight trip to the Purple Passion Mine, we found some very nice specimens (although we had to battle our way through the thorny vegetation and brave dozens of scorpions to pick up some of the pieces). My 8-year-old son and I met several other people at the mine in the early afternoon, which allowed us enough time to set up our campsite and to expose some fresh fluorescent material while it was still light out. At this time, the best fluorescent material is found on the surface where the vein is exposed on the side of a hill, so we used the usual chisels, hammers and crowbars to break off pieces of the vein. When it got dark enough, we checked the new material we had exposed and were rewarded with pieces which fluoresced three or more colors. The whole side of the hill fluoresced quite impressively. Under shortwave ultraviolet light, the calcite fluoresces cherry red, bubble-gum pink or fire orange, and the willemite hues are from white to yellow to shades of green. Although the fluorite and caliche fluoresce slightly under short-wave, with long-wave ultraviolet light, the fluorite ranges from tints of blue to a brilliant neon violet, the caliche exhibits pale yellow to peach-colored shades, and some of the wulfenite fluoresces a weak orange. No one has performed any testing on the material yet to determine what the specific phosphors are that cause the minerals to fluoresce.
During the first six months or so, we had only mined for crystal specimens and it was just due to luck that we discovered there was some top-notch fluorescent material at the mine. A collector from Michigan wanted some wulfenite and happened to ask if any of the material was also fluorescent. We said we didn't know but that we would borrow a black light and we would find out. I'm sure glad he asked us that question!
After collecting all the fluorescent material we wanted at the main site, we decided to use flashlights and our portable black lights to check out the rest of the vein. The vein is exposed intermittently for about 3,000 feet and it disappears under the washes and shows up again in the next hill. Collecting fluorescent minerals at night in the Sonoran Desert of southwestern Arizona has its own thrills and hazards. At night, it is much more difficult to follow a vein because of the desert vegetation and critters. In addition to the cacti, every tree, every bush and every weed with thorns seemed to reach out to grab our clothes and stab our skin. As for the critters when we waved our black lights around to follow the vein (which mostly fluoresced only a dull red), we were quite surprised to see dozens of scorpions. These scorpions were about 1 1/2 inches long and they fluoresced a bright yellow-green color themselves! It's a little scary to think that we probably walked right past many other critters without even seeing them, because the area does contain gila monsters, lizards, toads, tarantulas, desert centipedes and various snakes.
About 2,000 feet south of the main collecting area, on the side of a hill, we found a section of the vein with some extremely interesting patterns which resembled neon-blue hieroglyphics on a background of deep red. The same area also had some small spots which fluoresced a sky blue, probably hydrozincite. We collected enough specimens at this spot to fill a 5 gallon bucket. Unfortunately, when we tried to go down the hill to the road leading back to the camp, we got stuck in a bewildering maze of thorny bushes and trees. We were not lost, we knew exactly where we wanted to go, but each path we started to take was blocked after a short distance by impassable thorny trees. It took us about 20 minutes (and we were down to only one working flashlight) before we found a way back to the road.
When we finally got back to the campsite, we enjoyed socializing around the campfire and one of the hot topics of discussion was the history of the mine. According to records from the Arizona Mining and Mineral Resources Department (located in downtown Phoenix), the ore vein was discovered by a Mr. A. B. Lovell around 1890 and the ore was mined on and off from 1901 until 1926. The ore assayed about 10% lead and 15 ounces of silver per ton. The mineralized vein is composed primarily of calcite with ores of lead and silver running throughout, and it also has thin stringers of willemite, fluorite and quartz. In addition to the usual tabular wulfenite crystals, the Purple Passion Mine produces some needleshaped crystals of wulfenite (acicular) and "fuzzy tabs" (needles growing on top of tabular crystals are properly known as epitaxial, acicular wulfenite on wulfenite). The wulfenite also occurs on a wide variety of matrices, such as wulfenite on quartz (clear, smoky, milky and occasionally amethyst) and wulfenite on fluorite, calcite or galena. Other associations include anglesite, cerussite, chlorargyrite, smithsonite, sulfur and willemite. The specimen sizes range from micromounts to small cabinet pieces.
In 1926-27, a mill site was erected and a medium-sized operation was started by the Diamond Joe Mining Company Inc. The main shaft was inclined to follow the vein and it reached a developed length of 325 feet along the dip, for an actual depth of 225 feet. A vertical shaft was used to haul the ore to the surface. It intersected the inclined shaft at a depth of 83 feet and continued down to 180 feet. Across the wash, another vertical shaft was driven to 500 feet deep and connected to the other tunnels. The first 225 feet were used as the main entrance to the lowest working level of the mine and the bottom 275 feet were used as a water reservoir. Roughly 135,000 tons of ore were removed and a total of 2,250 feet of tunnels, shafts and stopes were driven, with levels at 45, 83, 180 and 225 feet. Late in 1928, the mine was closed because of insufficient water to process the ore. Except for some concrete bases, not much remains of the original mining operation. There are verbal reports that around 1974 some collectors were able to access the original tunnels and a few cabinet specimens were found which had wulfenite crystals up to 3 inches across. Unfortunately, at this time all of the old shafts are collapsed near the surface and attempts to reopen the original inclined shaft have failed so far. Indications are that the 43-foot tunnel is also likely to be collapsed. Further, old written reports indicate that surface water has filled the mine to fairly high levels. We think the 83-foot level may be the lowest set of tunnels that remain above water, and in a rainy year even that level may be flooded.
Another topic of discussion was now enjoyable it was to camp there. One really nice thing about this part of Arizona is that there are not very many mosquitoes, which makes the camping much more pleasant. Also, that far out in the desert, there is almost no light pollution so that the stars are absolutely wonderful to behold. The Milky Way looked like a river in the sky. (Have you ever tried explaining to an 8-year-old what the Milky Way is?) This particular night happened to be at a time when there were meteor showers, so we saw a shooting star about every 10 minutes. Too bad the most recent comet had already passed beyond view.
The next day, we worked the mine for mineral specimens. About 100 feet away from the original inclined shaft, a new shaft has been driven to a depth of about 45 feet. This shaft is producing the newest specimens of wulfenite and other minerals. The current shaft starts at a place where the main vein was mostly a fine-grained purple fluorite matrix, about 2 feet thick, with small amounts of calcite, quartz and galena. This shaft of the Purple Passion Mine is eventually expected to connect with the old Diamond Joe tunnel system, probably down at the 83-foot level.
When we were working the mine, we were startled by an encounter with a 3 foot rattlesnake. We were bringing 5 gallon buckets of material up from the shaft to spread on a tailings pile for examination. The rattlesnake magically appeared right on the tailings pile between the dumping out of one bucket and bringing up of the next. After several attempts to shoo it away (which produced much hissing and rattling), I managed to pick it up on the end of a long stick (for short periods of time at least) and moved it in stages far enough away so that it wouldn't bother us anymore. My son was quite impressed with all the hissing and the rattling, and I think it was a very good learning experience for him (I sort of enjoyed it also). I did notice for the rest of the day that he didn't go more than 10 feet in any direction without stopping to look around for snakes.
Throughout the day, we found some pretty nice specimens of most of the minerals we were looking for, and we considered the overnight excursion to be a complete success. In the late afternoon, we packed up the camp and headed for home. Back in Wickenburg, close to where Constellation Road ends, there are a number of places to eat, but with an 8 year old along, no trip is complete without a stop at the McDonald's for a happy meal.