`Tucson 2022 has completed its stay in the “Old Pueblo” and featured tens of thousands of mineral and other items to ogle at, or perhaps even purchase. The Tucson Gem and Mineral Show® completed its 67th version in the second week of February and incorporated material from the cancelled 2021 event (Fluorescent Minerals) with the original 2022 theme (The Apatite Supergroup). More information on this “main show” will come in a later post.
The “main show” is sponsored by the Tucson Gem and Mineral Society and is restricted to the one show in the Convention Center. However, there are numerous other events scattered around the city in motels, big tents, little tents, gravel parking lots, permanent buildings, and the beds of pickups. At one time most of these ancillary events started two weeks before the last day of the “main show.” However, since these shows are self-regulated, they now start and close on their own schedules, and this year several events started on various dates in January.
The largest of these ancillary shows is the Mineral City Show located north of the Tucson City Centre along Oracle Road. According to Graham Sutton the idea of forming/building Mineral City was conceived around 2018 when he asked several dealers if they were interested in establishing permanent showrooms for their collections. Today, after several setbacks mostly concerned with Covid, Mineral City has constructed several permanent buildings and remodeled others and is anchored, at least by people who remember, the old La Fuente eating establishment. The so-called warehouses are subdivided into different sizes of rooms that serve as selling venues, offices, and in the off season as storage areas. The selling venues are often furnished with fantastic glass display cases, tables for specimens, overstuffed chairs for resting and visiting; the dealers are mostly middle to high end. There is also a cantina and snack area snuggled in. I counted 121 different selling establishments with room for perhaps a few more in future years.
The Mineral City concept is an interesting experiment! In visiting with some dealers, I got the idea that perhaps some stores would have selling events scattered thru the year, perhaps before Christmas as an example. I also heard “gossip” that the only people at the 2022 event were collectors and the “general public” and visitors did not show up. I attended Mineral City on four different days and the traffic thru the selling areas was light (at least in my opinion) and one long time dealer told me that it was his worst Tucson selling event—ever. My biggest concern for the event is a lack of parking. Few gravel lots are available and parking on curb-less, pothole filled, roads is tough, at best. Handicapped parking is sparse. However, I wish Mineral City the best.
My favorite dealer in the Tucson shows, Mike Shannon of Shannon Family Minerals, was located in Mineral City and occupied a large room packed full of flats filled with a variety of minerals with reasonable prices (great for a frugal collector like me). It took me several hours for a cursory search of the flats; however, I did come up with several goodies, especially from the collection he purchased from Mineralogical Research Company.
One of my new specimens is from a favorite Utah collecting site, Gold Hill, an old mining community located south of the bi-state town of Wendover, Nevada/Utah, that was mined for gold, copper, zinc, lead, arsenic, and tungsten from the mid to late 1800s until the late 1940s. The peak activity was in the early 1900s when a spur railroad reached the area in 1917. There was only sporadic mining after World War I.
Gold Hill or the Clifton District, contains numerous mines, including an open pit, and is located near the northwest end of the Deep Creek Mountains, perhaps Utah’s most isolated and unknown mountain range. Peaks do reach 12,000 feet—Ibapah Peak at 12,087 and Haystack at 12,020. The Deeps are the major topographic feature in western Utah. The range has a Precambrian core surrounded by Paleozoic sedimentary rocks with later Mesozoic intrusions—mostly quartz monzonite and granite/granodiorite, and later Tertiary volcanics.
I have described a number of minerals [in this Blog] from the Gold Hill District and refer readers to the Post of January 3, 2015, where the mineralization is described in greater detail. Today I want to add the mineral zálesíite [CaCu6(A2O4)2(AsO3OH)6-3H2O] to my list. This somewhat rare hydrated hydrous calcium copper arsenate was not named and described until the end of the 20th Century (Sejkora and others, 1999) from the Czech Republic, and noted from Gold Hill soon after (Adams. 2005). Previously, known (at times) specimens of zálesíite were called agardite-Ca or REE-free agardite. Agardite is a REE-dominant hydrated hydrous copper arsenate that is a member of the Mixite Group and is in a solid solution relationship with zálesíite (Sejkora and others, 1999). The Mixite Group, according to MinDat.org, is a “group of chemically complex, visually indistinguishable arsenates and phosphates.” I have described, in past postings, mixite from the Gold Hill and Tintic areas in Utah.
zálesíite ~1 mm in diameter with green spheres of conichalcite [CaCu(AsO4)(OH)]. With a binoc scope the sprays appear to be pale green in color.
Zálesíite is the calcium- and arsenate- dominant member of the Mixite Group and forms from chalcopyrite and arsenides in conditions of supergene zone in-situ weathering (Sejkora and others, 1999). The crystals of zálesíite are: acicular and needle like, very minute (usually less than half a millimeter in length), often forming radiating small masses, generally transparent, very soft (~2-3, Mohs), having a semi vitreous to silky luster, and are said to be pale green in color. However, crystals on the specimen I have are more “pale white” in color and match the photos on Mindat.org of other specimens from Gold Hill. In reality, I am depending on the identification of the Mineralogical Research Company since Mindat.org states, members of the Mixite Group are “often only unambiguously identifiable by quantitative electron microprobe analysis.” This is sort of above my pay grade!
And speaking of Gold Hill----I also picked up another mineral from that locality (collected from Alvarado Mine) at the Show: spadaite. Well maybe a mineral since Mindat.org offers this opinion: “questionable species with unknown structure. No x-ray pattern has been published in the literature.” However, spadaite has been around for a long time since its initial description in 1843 from Italy (von Kobell).
The magnesium silicate spadaite [MgSio2(OH)2-H2O(?)] is a nondescript, colorless to cream to pinkish, soft (2.0-2.5 Mohs), amorphous, dull, mineral. It forms massive (no visible crystal structure) “hunks” with no visible crystal structure that sometimes are felted and shreddy, or sometimes dense porcelain-like. Spadaite seems limited to areas of skarn rocks (AKA tactite) where contact metamorphism and metasomatism affects carbonate rocks. At its type locality in Italy spadaite is associated with leucite-bearing basalt, in Germany with amygdular diabase.
Spadaite was first noted from the Gold Hill area by Schaller and Nolan (1931) as they prepared for Nolan’s seminal paper on Gold Hill (1935): “During the survey of the Gold Hill quadrangle in west central Utah, several specimens of an unusual type of gold ore were collected by one of us (T. B. N.). On microscopic examination these specimens were found to contain considerable quantities of a fine grained shreddy mineral which could be referred only to the very rare mineral spadaite on the basis of optical and chemical.” He noted that spadaite only occurs in the ore shoots and is associated wit the siliceous silicates wollastonite, garnet, diopside, and others. He believed that spadaite preferentially replaced wollastonite but was definitely younger than the original calcsilicate, contact metamorphic mineral (CaCO3). A follow-up paper by University of Utah graduate student H. El-Shatoury and his advisor James Whelan (1970) briefly noted Nolan’s description of spadaite but preferred to use massive-bladed wollastonite for the major skarn mineral.
Today one does not see many specimens of spadaite on the market and Mindat.org shows only 8 photos, half of which are from the Alvarado Mine at Gold Hill. So, I would say that it is not an attractive nor popular or common mineral.
REFERENCES CITED
Adams, P.M. (2005): Zalesiite from the Gold Hill Mine, Toole County, Utah: Mineral News, v. 21, no. 8.
Nolan, T.B., 1935, The Gold Hill Mining District, Utah: USGS Professional Paper 177
Schaller, W.T. and T.B. Nolan, 1931, An occurrence of spadaite at Gold Hill, Utah: American Mineralogist v. 16.
Sejkora, J., T. Řídkošil, and V. Šrein, V.,1999, Zálesíite, a new mineral of the mixite group, from Zálesí, Rychlebské hory Mts., Czech Republic: Neues Jahrbuch für Mineralogie, Abhandlungen v.175.
Shatoury, E.L. and J.H. Whelan,1970, Mineralization in the Gold Hill Mining District, Tooele County, Utah: Utah Geological and Mining Survey Bulletin 83.
von Kobell, F.,1843, Ueber den Spadaït, eine neue Mineralspecies, und über den Wollastonit von Capo di bove: Journal für Praktische Chemie v. 30.
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