By Merrill O. Murphy

I have not been down at the Rabb Canyon moonstone site for quite a long time, and I doubt that more than a few of our members have ever been there. There are reasons for that. 1) It is quite a few miles down there, 2) one must walk a few miles off the road on a moderately difficult trail, 3) unless you have a vehicle with rather high clearance, you will be forced to leave it where vandals may see it, and 4) you are faced with the choice of camping overnight or driving another 25 miles or so to find a motel room in Silver City. Believe me that it is well worth all those troubles.

Back in the 1960’s, another Albuquerqian and I held mining claims on the moonstone deposit. However, we were not the first to do so. I think that the first claims may have been worked as far back as the earliest copper mining in the Silver City area. Then, again, perhaps not. At any rate, those who tried to mine those wonderful moonstones ran into the same problems that my partner and I faced. There is no road into the site, so it is very difficult to bring in equipment. Then, too, great care must be taken when trying to separate the moonstone from the worthless rock. The old drill-and-blast technique just shatters the moonstone. The only procedure possible seems to be careful chiseling using a dull steel chisel and hammer. For the casual collector, the most practical technique is collecting loose material from the surface and/or raking the loose sand to uncover loose moonstone pieces.

Ruth Bronson, an old-time facetor from west Albuquerque, became tired, sat down on a low bank, and scuffed the sand with her feet. In doing so, she uncovered a chunk of moonstone weighing several pounds. Only parts of the chunk were cuttable into bright silvery-white stones. Like most of the white moonstone, this one was nearly opaque but much, much brighter than the moonstone of India and other eastern countries. This specimen came from the north end of the site. Pieces taken from the southwest end are generally smaller, but the moonstone glow is a transparent sky blue and wonderful for faceting small gems.

Moonstone is a member of the feldspar family of minerals. Feldspars are the most common of all crystalline minerals. There are numerous feldspars and feldspar-like minerals. Most of them are listed as orthoclase (potassium-aluminum-silicate with varying crystal structure) or plagioclase (calcium-sodium-aluminum-silicate with the calcium and sodium varying with subtypes). The Rabb Canyon moonstone is a member of the orthoclase group called sanidine. Sanidine is a “high temperature polymorph of monoclinic orthoclase” and is much less abundant than other members of the orthoclase family. It tends to form as euhedral crystals with tetragonal Baveno twinning.

I have two very technical treatises on Rabb Canyon. One is titled, “Shallow, High-Temperature Pegmatites, Grant County, New Mexico” by V. C. Kelley and O. T. Branson. It is reasonably readable. The other is titled, “Preservation of Primary Magmatic Features in Subvolcanic Pegmatites, Aplites, and Granite From Rabb Park, New Mexico by James D. O’Brient. This second one tends to use all the tongue-tangling words the author could find in the dictionary. For example, the O’Brient article uses seven huge words on the first page. Examples are “consanguineous”, “phaneritic”, and “hypabyssal”. Though tending toward the complex, both articles contain a great amount of information. Both should still be available through the University of New Mexico Library and the New Mexico Institute of Mining and Technology Library.

Now, how does one get to the Rabb Canyon site? Simple. Follow U. S. 25 south to Truth Or Consequences. About 10 miles south of T Or C, turn west on paved State Highway #152. Continue west, more or less, through Hillsboro and Kingston. Stay on State Highway #152, climbing steeply over Emory Pass. Check your odometer at the top, then drive carefully down the west side of the pass for about 10 miles. At this point, the road flattens momentarily before leaving the valley and climbs to the top of a low hillside. Slow down and watch carefully on your right as the road goes gently downward. Watch for an opening in the trees with a livestock corral at the back of the open space. Drive, perhaps, 50 feet, toward the corral. Then, turn west (to your left) for 75 feet. Stop and examine the dirt road leading west into a gully. Make sure your vehicle has enough clearance to continue. IF NOT, YOU MUST PARK IN THE CLEARING OR DO ENOUGH ROAD WORK TO MAKE CLEARANCE PRACTICAL. Walk or drive down this primitive road to a shallow valley (Noonday Canyon), where it turns to the north and crosses a shallow ford. (There may be a trickle of water here). Cross and continue beside an old fence line until you reach another clearing, a distance of, perhaps, 200 yards. There is an east-to-west fence and gate just beyond the clearing. This clearing is the trailhead. If you have driven in, then pull off the road and park here.

Climb the ridge on the west of the clearing, going, perhaps, 20 to 30 degrees north of west.You should reach a distinct trail near the top of the ridge. This trail runs north a short distance to a second gate in the fence mentioned above. After reaching this second gate, the trail angles and goes nearly west across the ridge. If, however, you have found no trail and no gate at the top of the ridge, then go back to the trailhead. Now, follow the dirt road north no more than 100 yards to the east-west fence. Then, walk west up the fence line until you reach gate #2 near the top of the ridge. From this ridge-top gate, the trail leads gently up and down a few hundred yards before diving abruptly into Rabb Canyon.     

Go up Rabb Canyon. There should be pools of water in the canyon bottom. If you look closely, then you will see bright blue flashes from tiny moonstones in the water. The canyon turns to the west a short distance upstream, and the water disappears in the sand. Continue up Rabb Canyon until you see a shallow arroyo on your right. There may be a trickle of water in the arroyo. Cross the arroyo and take a trail leading northwest. This trail goes only a short distance before crossing the arroyo. Follow the trail paralleling the arroyo, keeping it no more than 50 feet to your left. After about a quarter mile, the indistinct trail will reach a livestock corral. Turn to the left and walk to the arroyo bank. About a half truckload of white feldspar should be visible on the far side. It is opaque, cracked, and shows little adularescence. It is part of a pegmatite that follows a fissure down from the main deposit.

Get down in the arroyo and go up it no more than 30 yards to a very indistinct gulch that joins the main arroyo from the west. This gulch leads to the moonstone site. Follow it more or less to the west. The banks will begin to steepen. Watch for a trail angling up the right-hand bank. This trail will climb out to a bowl-like little mesa measuring no more than two or three acres. Majestic cedar trees stand tall in the bowl, some of the largest cedar trees I have ever seen. When you climb out of the gulch, continue a short distance west. You should see the remains of a tiny cabin. Blue moonstone is scattered on the sands between the cabin remains and the lower edge of a sharp ridge. Silver-white moonstone comes from the north part of the bowl. Shallow prospects are visible here and there along the west and north edges of the bowl. You will find lots of fine but very small bits of blue moonstone. The white moonstone will be in larger pieces. Few pieces of either will yield good cut stones.

Single moonstone crystals at this site have been reported as large as 13 inches by 13 inches by 20 inches. Quartz crystals as large as three feet long by 8 inches diameter have also been taken from this site. The quartz varies from colorless to jet black and smoky. Shallow trenches at the north end of the deposit have yielded pale amethyst. Some of the large crystals of quartz show as many as five growth interruptions, indicating numerous periods of intense volcanic action. There are other minerals, such as biotite, magnetite, ilmenite, and sphene that have also been reported here. Tiny blue crystals of sanidine feldspar occur in rhyolite from many places in New Mexico, but this seems to be the only known pegmatite producing large crystalline sanidine.

Now for a few precautions. First, be careful on the trail down into Rabb Canyon. It is steep, and there are several places where a stubbed toe can initiate a painful fall. Second, you will be sharing this wilderness area with wild animals and semi-domesticated animals, like cattle. The cattle will probably be no problem, but stay clear of a bull or a cow with a baby calf. Third, among the wild animals to be aware of are bears, mountain lions, and rattlesnakes. Bears and lions will generally be more afraid of you than you are of them. As with cows and their calves, a mama bear or lion is unpredictable should you come between her and her baby. Always be wary of rattlesnakes. Several varieties of rattlesnakes reside in the Rabb Canyon area. The most dangerous variety is a small, dark, gray-green rattler. These blend so well with their surroundings that they are difficult to see. They are also very fast. Be attentive to the surroundings, and be careful of where you step and place your feet.

I once walked alone into the moonstone area to take some pictures. I have since decided that going alone was a bad idea. I parked my low-built car just off the paved road in the first clearing. I returned to the clearing several hours later, unlocked the car door, and placed the camera inside. That is when I heard a rattling noise. I looked around but saw nothing. Wary, I stood watching the area where the noise seemed to have originated. The rattle came again, someone’s discarded tin cans maybe. Then, about 25 feet away, behind a three-foot boulder, the rattle came again. A patch of dark brown fur showed momentarily above the boulder. I picked up a fist-size rock from down by my feet and threw it over the boulder. Thirty pounds of baby bear stuck its head over the boulder. Another rock launched in his direction sent him waddling toward shelter. With my car door open, I stood scanning the area, looking for mama bear. I never did see her, but you can bet she was not far away. The morale to the story is: when out in the wilds, walk carefully, always remain on the watch, AND NEVER GO ALONE!