The Story of Whewellite in Cochise County Arizona
By Rolf Luetcke

This is a story that goes back a few years on our own property. We had two large agave plants, often called century plants, die on one section of our property. After the stalks had dried out completely, I cut them off at that base, near the very defensive leaves and used the stalk along the fence by our drive to attach for birds to land on the upper branches. The bases of the agaves were dangerous because of the very large spines not only on the tips but also the curved spines along the leaf margins. So, those stayed in the ground. I didn’t give them much thought until a few years later and since they were in a spot we don’t often walk, I had not noticed anything before. This one sunny day, I happened to be near the dead agave bases and saw something interesting. The center of the remaining base was totally sparkly with reflections. It was like thousands of tiny diamonds reflected in the sunshine. Collecting minerals, I knew well the sparkle often meant crystal faces.
I got a box and a couple of tools that allowed me to avoid the nasty spines and collected some of the material. The spines are known to have a coating of an alkaloid that makes a puncture hurt a lot so I stayed well clear of the spines. Took the material in to my microscope and immediately was amazed by the masses of tiny, colorless, bladed crystals. I knew of crystals that can form in dead Saguaro cacti and had a couple of them in our collection. These are weddellite crystals and since we don’t have the Saguaro’s here in the neighborhood, I had purchased a couple of specimens. There is also lansfordite and it is also one which forms in the dead Saguaro cactus and we have specimens of this as well in our collection. These in the Agave were completely different in habit and I started doing some research on the calcium oxalate crystals that grow in dead cacti. Turns out the bright crystals I came across in the Agave were most likely whewellite. I took a number of photos of the crystals under the microscope and posted them for our local Saint David Arizona page on mindat.
A friend at the Tucson mineral show one year was very interested when I mentioned those crystals and he collected and sold those kinds of crystals so next visit to Tucson I brought him a couple of boxes of the material full of those crystals from the dead agave. That was the last I thought about these crystals for a number of years. I had put a few in our collection but had not thought much of them until a Tucson friend contacted me about those crystals he had seen in my photos. The whewellite crystals he was familiar with were quite different looking and he wondered if we had any we could send him to analyze. This I did and it was then a wait until he had time to check them at the lab.
The result for me was to think about the whewellite photo he had sent me from a prickly pear cactus plant. On our 5 acres of land we have a multitude of cacti and had been enjoying them for many years. In the last couple of years we have had a fungus that has hit our prickly pear cactus hard and many pads had been dying. Just when the friend contacted me I had actually been cutting off the dead pads and disposing of them in a couple of places on our land. So, the fact he had a photo of some whewellite in the dead pads had me go out and collect a few pads and take them to my work table, carefully cutting them into manageable pieces to view under the microscope without getting hit by too many of the spines. Even with leather gloves a few made it through and got me. As soon as I got the material under the microscope, I saw that there were indeed whewellite crystals all over the dead tissue inside the outer shell of the dead pads. This was a nice surprise to me and I mounted a few of them after taking some photos.
Next was to go out to the property and check a couple of other cacti. The first was a cholla cactus called Cane Cholla. Those have nasty spines and I took a good bit of care to extract the dead tissue without getting full of spines. Sure enough, those also had the whewellite crystals. One cactus after another I went out and found some dead parts and cut them open to inspect. Every one had the crystals in the dead tissue. A couple of the cholla cacti are very small and only a half cm across the joints so the study of those was not as easy as the larger ones. Those also had the whewellite in them, smaller clusters of crystals but there they were. The smaller Cholla were the Desert Christmas Cactus and the Pencil Cholla. There is one larger one also called Buck-horn Cholla and it had some of the nicer clusters of the whewellite crystals inside the dead tissue.
Then I decided to see if our large cactus called the Arizona Barrel Cactus had them and we had a dead one which also produced the crystals. Then to a Pink-flowered Hedgehog Cactus and again there they were. In all we checked 8 different dead cactus pads and joints and they all contained the crystals.
After having cut off a lot of the dead and dying pads to clean up our cactus garden, some of the dying ones were full of a very stinky green liquid. I am sure as this was drying out the minerals that the live cactus had in the fluids to keep it healthy were an ideal solution to form those crystals as the liquid slowly dried out. Even the smaller cacti had the same kinds of liquids that when drying allowed those crystals to form.
On each species of our cacti I was able to get photos of the whewellite crystals and post those to the St. David, Cochise County, Arizona page.
When the friend did the analysis, we were both hoping the agave crystals would be a different calcium oxalate but he said he ran the samples twice and they turned out to be whewellite as well. We were both surprised, only because the crystals had taken a much different form in the agave as they had in the cacti. He had also found a dead agave near Tucson and found the same elongated crystals I had found on our property. We don’t know why the crystals are a different habit but they did turn out to be the same mineral.
The whole small adventure started with his seeing the photos I had on mindat and this led to a week of dead cactus tissue study to find all the various plants that had the whewellite crystals in them.
There are other cactus species in our area also but I have not come across any dead ones I can study the old tissue to see if they also contain the crystals. I will have to keep my eyes open and when I come across some bring them home.
This was a case of the minerals were all over on our own property, right under our noses and we had no idea they were there. Today I passed along some of the agave crystals to a friend and explained they were also in the dead cactus tissue only in different crystal habit. He was looking forward to getting home and looking for some dead cacti on his property to see what he could find.
Bit of an update on the whewellite on our property, we kept looking in other plants as well and now have found the crystals in 11 different cacti and other related plants. The latest was to find the crystals in Yucca plants. The habits of the whewellite crystals do seem to vary quite a bit from the rounded balls with small triangular crystals to some which were flattened and elongated to nearly acicular crystals. Don't know whether it is our local soil that allows so many plants to get the crystals after they die since we have only explored the plants in our immediate area but it makes me wonder how wide spread this mineral is in the dead cacti and plants.
Have taken photos of all the plant related whewellite crystals and posted them to the Saint David area page. Hope this article gives others the idea of possibly looking for the mineral in their areas.