One of the big venues of the Tucson Shows is held at the Hotel Tucson City Center (HTCC). The 292 vendors come from around the world and sell a variety of minerals, rocks, fossils, shipping boxes, books etc. Unlike some venues, for example Kino, the vendors are selling treasures with a geology connection. I believe these vendor standards are due to the promoter, Coloradan Marty Zinn.
The vendors at the show display their wares in the large ballrooms as well as most of the hotel rooms.
|This is an interesting specimen of quartz. Does not look like quartz? Well it is a pseudomorph after anhydrite.|
Every kid interested in dinosaurs would love this replica of a poor ole plant eater being zipped by a couple of small raptors.
Nice therapod (meat eater) skull. Note those massive shearing Nice therapod (meat eater) skull. Note those massive shearing teeth.
This display is available every year and I love it. There are fake Moroccan trilobites, and other critters, all over the place. It is hard to say but a good guess might be 75%?
This is a “real” fossil from the western Kansas chalk beds (Niobrara Formation): Xiphactinus, the “Bulldog Fish.”
|Glen Rockers of www.paleosearch.com always has nice displays of Cretaceous vertebrate fossils from the Kansas chalk beds.|
Before leaving for Arizona and the Tucson Shows I received my copy of Rocks and Minerals and was delighted the issue centered on “blue minerals” to correspond with the theme of the main Tucson Show. One of the magazine articles was a description of the mineral carletonite, a new one for me [KNa4Ca4Si8O18(CO3)4(OH,F)-H2O]. I noted it was such a gorgeous royal blue color but sort of put it aside in my mind as I saw descriptions such as rare, expensive, and “finding a fine specimen of carletonite today is nearly impossible. And the outlook for the future is not promising…” (Pohwat, 2016).
|Photomicrographs of carletonite with enlargement above. Width FOV bottom ~8 ,mm. Both royal blue and clear material can be observed.|
The colorful carletonite is that beautiful royal blue color although some crystals are colorless, pink or light blue. Many of the crystals are zoned with blue centers surrounded by colorless crystalline material. This type of zonation may be seen in photos of my specimens. The crystals range from transparent (colorless material) to translucent (blue material) and have a vitreous luster. They are somewhat soft at 4.0-4.5 (Mohs) with a white streak. The crystals (Tetragonal) tend to be prismatic although this feature is difficult to discern on smaller fragments.
Mont Saint-Hilaire is a fascinating mineral locality. MinDat lists 404 valid minerals collected from the quarries with 63 of the species being first described from the locality. What makes the locality so special? Powhat (2016) noted the dominant rocks at Mont Saint-Hilaire are feldspathoidal seyenite, an igneous intrusive rock composed of alkali feldspar, a feldspathoid, and accessory minerals. The feldspathoid minerals are usually sodalite (sodium aluminum silicate chloride) and nepheline (aluminosilicate of sodium and potassium).
Feldspathoid-rich rocks (wherever they occur) often produce a great variety of rare minerals, including carletonite. A glance at MinDat will often amaze the rockhound since the list of minerals (the 404) is a lesson in “what in the world is that mineral?” Besides the seyenite, carletonite also evidently occurs in metamorphosed siliceous limestone: marble (www.webmineral.com).
Pohwat, P.W., 2016, Carletonite, Mont Saint-Hilaire, La Vallee-du-Richelieu RCM, Monteregie, Quebec, Canada: Rocks and Minerals, v.91, no. 1.