TUCSON INN SUITES: KARIBIBITE & FRANCKEITE

 The Arizona Mineral and Fossil Show at Hotel Tucson City Center has been a staple show for many years.  Many rockhounds refer to the show as the Inn Suites; however, changes are a coming. I certainly am not privy to the “real information” but vendors are leaving the Show and moving on due to—who know—contracts fights or something?  At any rate the “official” Show will move next year to the Hilton El Conquistador north of downtown Tucson in Oro Valley.  Some vendors have already moved to the Old Pueblo Show and also to the new Mineral City Show. I suppose we will know more in 2021.

The Arizona Mineral and Fossil Show has a couple of different formats: 1) the hotel rooms on two floors of a horseshoe shape arrangement are filled with vendors; 2) the “ballrooms” inside the hotel, and the lobby, have vendors, including some very large displays.  It seemed apparent to me that vendors have left for “greener pastures.”

The motel rooms, two stories, were not overly busy during my visit.  Many vendors were interested in visitors chatting about rocks and minerals.  I found Joe Dorris of Colorado Springs in one of these rooms; however, Joe had his crew scattered out in 4 or 5 different shows.

Other dealers occupied large ballrooms.

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Here is a dealer with a few tables outside the lobby.

Cenozoic sand dollars that seem pasted on the matrix?  Maybe not?

The "most popular" mineral from the last couple of years has been brucite.  It was still around in abundance this year but not as expensive.

Carved bowls, some quite large, were very popular this year.

How about a Pleistocene Lion?  Panthera leo spelaea from Romania.

Green River (Eocene) fish from Kemmerer, Wyoming are everywhere.  They are now preserved from collecting at Fossil Butte National Monument.

Black Hills Institute from Hill City, South Dakota, displayed some nice marine reptilian teeth. 

I did find a couple of specimens that were of interest, so they joined my collection: 1) karibibite with schneiderhöhnite and löllingite; and 2) teallite or franckeite.  As I noted in my previous text, life-long learning is just fun!

After numerous attempts I finally was able to get a decent photomicrograph of these sprays of karibibite. Each of these individual prismatic crystals are submillimeter in length.

So, what about the iron plus arsenic minerals? Karibibite is a beautiful, but rare, arsenite consisting of microscopic, orange yellow, sharply pointed, radial sprays of fibrous crystals usually less than 1 mm in length.  They are very soft and may be flexible and with a yellow streak. Karibibite is found in granite pegmatites and seems to be a weathering product of löllingite   but is often associated with schneiderhöhnite. Although it is awfully easy to call karibibite an iron arsenite (it is) the chemistry is quite complicated (at least for me) as there are two structurally different arsenite anions (the negative charged oxidation state); however, the numbers seem to “add up.”  Fe³⁺₃(As³⁺O₂)₄(As³⁺₂O₅)(OH) is the formula from MinDat.  So, the iron is 3+ x 3=9+ for the cation; the first anion is 3+ for the arsenic and the oxygen is 2 x 2- = 4- for a total of 1- times the 4 parts= 4-; and  the second anion is 3+ x 2= 6+for the arsenic while the oxygen is 2- x 5 =10- for a total of 4-; the hydroxyl is 2- for the oxygen and 1+ for the hydrogen= 1-.  The 9+ cation then is equal to the first anion 4-, the second anion 4-, and the hydroxyl 1-.  Please be aware that this little chemistry is just an exercise to??? Sharpen my brain, I guess.  It really does not be much to most rockhound readers. 

Several sprays of karibibite housed in very reflective löllingite.

Karibibite is almost always found in vugs of löllingite, an arsenide—iron plus arsenic, FeAs₂.  Again, the iron 2+ is the positive cation while the arsenic 1- serves as the negative anion (arsenic has a variety of oxidation states).  Trying to describe löllingite is sort of tough.  It is a shiny, silver-white to steel-gray mineral with a metallic luster, a medium hardness of ~5.0-5.5, has a gray-black streak, is brittle, and has an “almost” conchoidal fracture.

Sprays of karibibite surrouned by löllingite with the dull metallic luster of schneiderhöhnite in lower right quadrant.

Karibibite also is commonly found with the schneiderhöhnite, an arsenite that contains both ferrous (oxidation state of 2+) iron and ferric iron (oxidation state of 3+):  Fe²⁺Fe³⁺₃As³⁺₅O₁₃.  The iron content imparts a black to brownish black color and a resinous to dull metallic luster.  At Mohs 3 it is softer than the 5.5 of löllingite and I used that property as a major identification tool.  It has a brown streak, is brittle and a platy/micaceous fracture. An old label indicated my specimen was collected from the Urucum pegmatite at Galilela,Minas Gerais, Brazil.

The second mineral that I picked up is labeled teallite, a lead tin sulfide---maybe!  The specimen was collected by David Shannon several decades ago from the San Jose Mine in Oruro Department, Bolivia.  MinDat states that “a great many specimens labelled teallite, especially those from the San Jose mine in Oruro are really franckite [iron lead tin antimony sulfide]…Franckeite from here is frequently mislabeled and sold as teallite.”  So, I am going with my specimen as franckeite (Fe(Pb,Sn)₆Sn₂SbsS₁₄)  with some minor jamesonite, a lead iron antimony sulfide (Pb₄FeSb₆S₁₄). 

Crystals of franckeite with a top layer of the needle-like crystals of jamesonite.  Essentially impossible for me to get a decent photo of this reflective mass of mixed up crystals.  I just don't have the equipment. Width FOV ~ 1.4 cm.

Photomicrograph of franckeite crystals with a small mass of jamesonite in upper right corner.

Franckeite is quite rare and an opaque mineral with the metals imparting a black to gray-black color and a metallic luster.  Typical of the metallic minerals, franckeite has a gray-black streak and is malleable. Crystals may be thin tabular, foliated, fibrous, massive or aggregates and fine-grained, or stellate. The cleavage flakes  are flexible and the metallic luster reflects light (like many metals).Franckite is soft at ~2.5 (Mohs). The mineral is found where carbonates encounter metamorphic rocks (contact metamorphism) and in polymetallic rocks reacting to hydrothermal fluids.

Jamesonite is a dark gray mineral that is common as masses of needle-like acicular, prismatic crystals.  It is soft at 2.5 (Mohs). It has a metallic luster and is opaque. It is a hydrothermal mineral and sometimes occurs with boulangerite (which it resembles).

The next series of Tucson Shows in 2021 will certainly be different for the Arizona Mineral and Fossil Show.  Will it be at the Tucson Center?  At Mineral City? El Conquistador Hilton?  Only time will tell.

Sometimes the questions are complicated, and the answers are simple.       Dr. Seuss

TUCSON KINO JERRY GARCIA,:VLASOVITE, & FLUORBUERGERITE

The weather in Tucson has been just pretty fantastic!  There was some rain during the two-week window for Shows; however, visitors could not offer many complaints.  The last weekend of the Shows the temps jumped to mid-70s and remained for the following week.


One of the really big venues in the City is the Kino Gem and Mineral Show, formally the Kino-Electric Park Show.  By my rough count there are ~240 vendors ranging from Idaho Bling Bling to Australian Mineral Mines.  A rockhound could easily spend a day wandering through indoor and outdoor displays.

Business is sloooow.

Rose quartz by the pound, but not very gemmy.

Outside stalls with large tents in the background.

Walkway through the smaller tents.

Colorado minerals for sale but pretty ugly.

Lots of filler holds this dino bone together.

Sea urchin with "glued on" spines. No disclosure.

There were not a large number of mineral dealers offering collectable  crystals but there were numerous stalls selling amethyst cathedrals, and massive quartz cut and polished into perfect terminated “crystals.”  Both were being marketed as coffee table décor. 
   

No mention of non-original parts on these trilobites

Bovine skulls at a minerals show?

And we can't forget Jerry Garcia and beads.

However, since every wild pig can find an acorn or two, I was able to muster up a couple of mineral specimens for my collection: vlasovite and fluorbuergerite.  Now why in the world would I chose those two minerals?  Mostly because I have posted on my desk a quote by the journalist Bill Moyers: When I learn something new, and it happens every day, I feel a little more at home in the universe, a little more comfortable in the nest!  My goal at this stage in my journey through the cosmos is to learn about a new mineral every week, not just its name but something more in depth (remember I am a softrocker/paleontologist and far from a mineralogist).  When I first noticed these two minerals, I did not have the slightest idea about their chemical composition, environment, or “anything” about them.  So, I decided that two orphan minerals relegated to the dusty back drawers would become my “learning project” for the week! 

THE GREATEST LESSON I HAVE LEARNED IN LIFE IS THAT I STILL HAVE A LOT TO LEARN     (unknown)

It turns out that vlasovite, a sodium zirconium silicate [Na₂ZrSi₄O₁₁],  has a pretty steep learning curve, especially when I try and understand the crystallography. For example, the silicate ion consists of a tetrahedron arrangement of four oxygen atoms surrounding a central zirconium atom.  So far, so good!  In vlasovite there are four of these tetrahedra joined together in a chain arrangement that then are bonded to zirconium octahedra (eight oxygen atoms surrounding a zirconium atom). I have drawn that arrangement out and “sort of” understand it.  What I fail to understand is how the sodium atoms fill channels in the arrangement.  Oh well, life is full of mysteries and I will continue to ponder that question—although maybe not in depth 😊


Another factoid where I need a mineralogist to answer, is “why.”  Vlasovite is a stable Triclinic mineral (three axes, A, B, and C all of unequal length and none are at right angles to each other)) below 84 degrees F.  Above this temperature vlasovite is a monoclinic crystal (three axes all of unequal length, two at right angles to each other while one in not at right angle).   Now, how does that happen? Is the Crystal System determined at “birth” or is there a change later in life?  Are the Crystal Systems reversible?  Don’t know.


Vlasovite occurs in rocks I will probably never see.  It was first described from the Kola Peninsula in Russia (1961) where it formed as a replacement for eudialyte during an invasion(s) by hydrothermal fluids.  In 1967 it was identified as an accessory mineral in miarolitic granite cavities on Acension Island in the Pacific. Finally, in 1973 vlasovite was identified as a primary mineral in metamorphic rocks of the Kipawa Alkaline Complex in Quebec, Canada (summary from Gittins and others).  Today the Complex is the major source of vlasovite material on the market. 

Different views of vlasovite associated with pink eudialyte (another zirconium silicate) and white chalky gittinsite (calcium zirconium silicate as an alteration product along vlasovite cleavage planes). Width FOV: bottom ~7 mm, top and middle ~1.1 cm.

Vlasovite is a tough mineral to identify unless it is associated with pink eudialyte (which it often is).  The color ranges from colorless to pink to light brown; often the latter color is due to microscopic inclusions. It is brittle with a conchoidal fracture and a hardness of ~6.0 (Mohs). It leaves a white streak and ranges from translucent (my specimen) to transparent with a pearly luster.  Crystals of vlasovite are quite rare and most specimens consist of irregular grains.


So, what about the fluorbuergerite? It turns out this mineral with a long name is an iron rich tourmaline. The original name was buergerite until the discovery of fluorine in the chemical makeup.  Superficially, fluorbuergerite looks much like the common iron rich tourmaline known as schorl; however, it is much rarer than schorl and MinDat lists only five worldwide localities.

Fluorbuergite crystals in rhyolite from Mexquitic, Mexico.  Width FOV: top ~5 mm, bottom ~1.4 cm.

Rockhounds often speak of tourmaline as a single mineral; however, mineralogists realize that tourmaline is actually a large group, ~40, of closely related minerals.  Most of us are familiar with such species as dravite (magnesium rich), elbaite (lithium and aluminum rich), and schorl (iron rich). Several varieties of Tourmaline Group minerals also  are recognized, mainly by gemologists—for example, cat’s eye {chatoyance), rubellite (pink to reddish), watermelon (color zoning of pink core and green rim), etc.  However, all members of the Tourmaline Group have a common chemical composition (MinDat):

A   (D₃)   G₆   (Si₆O₁₈)   (BO₃)₃  X₃   Z  

A=calcium, sodium, potassium, or is vacant. Cations.

D= aluminum, iron lithium, magnesium, or manganese. Cations.

G= aluminum, chromium, iron, vanadium. Cations.  

Silicate ion; cyclosilicate (AKA ring silicate). Anion.

Borate ion; Anion

X= oxygen and/or hydroxyl (OH). Anion.

Z= fluorine, oxygen and/or hydroxyl. Anion.

So, A, D, and G are positively charged cations  while the silicate, borate, fluorine, oxygen, and hydroxyl are negatively charged anions. 


The borosilicate and fluorine-rich fluorbuergerite has a chemical  formula of: Na(Fe³⁺₃)Al₆(Si₆O₁₈)(BO₃)O₃F and is a bronze-brown to dark-brown color (although almost appearing black), often with a brown schiller, and imparts a brown streak on unglazed porcelain.  It is generally opaque but may appear translucent in thin slices and a strong light. Like other tourmalines it is hard and rates a 7.0 (Mohs). Crystals are long to short prismatic and often terminated.  The best distinguishing feature—bronze to brown tourmaline crystals collected from rhyolite cavities found at Mexquitic, San Luis Potosi, Mexico.

REFERENCES CITED

 Gittins, J. E.L. Gasparrini, and S.G. Fleet, 1973, The occurrence of vlasovite in Canada: The Canadian Mineralogist, v. 12.

TUCSON: BEYERITE, TALMESSITE, & HIDALGOITE

As I noted in my last posting I will not make it to all 51 of the Show venues—not enough days in the two weeks and not enough hours left in my legs.  So, I pick the venues carefully (I am not interested in the thousands of Moroccan fossils, along with vanadinite, that fill many venues).  I am now off to the Mineral Habit venue, a Show that is “”new to Tucson.  Actually, the dealers moved out of the “Slaughterhouse” on Grant Avenue to vacated buildings on north Oracle—a good move with nicer facilities.  The group of dealers is anchored by Shannon Family Minerals, an internet dealer. with a huge inventory.  Mike Shannon always has some interesting, and often rare, minerals for sale. 

I picked up a thumbnail of beyerit (beyerite in the U.S.) with an old German label: Johann Friedrich Mine, Murgtal, Schwarzwald.  The Murg is a tributary of the Rhine River while Schwarzwald is German for what we call the Black Forest.  Both are in the State of Baden-Württemberg in the southwest part of Germany bordering France. The only reference I could find for the Johann Friedrich Mine was in MinDat and labeled as: Königswart Mine (Johann-Friedrich Mine), Schönegründ, Baiersbronn, Freudenstadt, Karlsruhe, Baden-Württemberg, Germany.  So, I will go with Mindat: Copper-Silver-Bismuth mineralized veins in sandstone. The mine was abandoned in 1826.

Beyerite is a bismuth oxycarbonate [has both oxide and carbonate anions], Ca(BiO)₂(CO₃)₂, and forms as a secondary mineral in oxidation zones of bismuth-bearing sulfates or sulfides, or perhaps native bismuth. However, I am uncertain about the Johann Friedrich as MinDat did not list any of these hypogene minerals, such  as bismuthinite, as being present although nearby mines have this primary ore mineral.
 

Crusts of gray to green beyerite.  Width FOV 9 mm.

Lathes of tan to light green beyerite each about 1 mm in length.

Beyerite has a variety of colors ranging from yellow to white to gray and shades in-between.  It is quite soft (2.0-3.0; Mohs), transparent to translucent, and has a luster ranging from dull to adamantine.  It belongs to the Orthorhombic Crystal System, but crystals are often hard to distinguish in earthy masses.  Some beyerite appears as flattened rectangular plates, or spheres of radiating fibers, or simply individual lathe-like crystals.

Beyerite is pretty “plain looking” in most cases and MinDat notes “it is visually indistinguishable from other oxycarbonates bismutite [(BiO)₂CO₃] and kettnerite [CaBiCO₃OF].”  So, my specimen is listed as beyerite; however, the label is “old” so perhaps quantitative work has not been performed of these specimens from the Johann Friedrich mine.  MinDat lists both beyerite and bismutite as coming from the mine.

I am always on the hunt for mineral specimens from Utah.  I have written other posts about the Gold Hill mine located in the western part of the state as it has produced a fantastic suite of minerals. Gold Hill is 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.  

Prismatic/stalactitic and translucent crystals of calcite, each 1-3 mm in length.  I am uncertain about spray of much smaller translucent crystals in the center.  Top photomicrograph has small,1 mm "balls" of austinite crystals (A) between the larger calcite crystals. 

A "ring" of talmessite crystals surrounded by very tiny austenite crystals and surrounding massive goethite.  Width FOV ~9mm. 

Gold Hill is home to an amazing number of arsenate minerals, those with the AsO₄ 3- oxidation state anion (arsenic has a 5+ oxidation state while the oxygen has an oxidation state of 2- for a total state of 3-).   One of the rare arsenates present is talmessite, a hydrated calcium magnesium arsenate: Ca₂Mg(AsO₄)₂-2H₂O).  The mineral has a vitreous luster and is  colorless or white; however, small amounts of nickel may turn it a pale green while cobalt will impart a characteristic pink shade.  Is has a hardness of 5.0 (Mohs) and is transparent (colorless) to translucent (white). Crystals may form massive crusts, prismatic/stalactitic groups, or aggregates of radiating fibrous microcrystals.  MinDat notes that talmessite is an oxidation product of realgar/orpiment (arsenic sulfide) or copper-nickel arsenides (such as skutterudite) and forms in the oxidation zones of hydrothermal ore deposits. 

Crust of green hidalgoite.  Width FOV 1.3 cm.

 

Boxwork of green hidalgoite.  Width FOV on above two microphotographs ~1.0  cm.

Another interesting Gold Hill arsenate picked up at the Mineral Habit venue is a rally nice specimen of hidalgoite:  PbAl₃(AsO₄)(SO₄)(OH)_6.  Hidalgoite is sort of non-descript usually occurring as a druse or spherulitic encrustation; however, at the type locality (Zimapan Mining District, Hidalgo, Mexico) the mineral occurs as dense white masses.  In some localities the mineral is colorless; however, the specimens I have observed from Gold Hill are tan to orange to shades of green.  In addition, the Gold Hill specimens are usually associated with “limonite” and secondary rust coloration may hide the true color.  and is a product of weathering in the oxide zone of metallic sulfide deposits (containing lead).  Hidalgoite is sort of non-descript usually occurring as a druse or spherulitic encrustation; however, at the type locality (Zimapan Mining District, Hidalgo, Mexico) the mineral occurs as dense white masses.  In some localities the mineral is colorless; however, the specimens I have observed from Gold Hill are tan to orange to shades of green.  In addition, the Gold Hill specimens are usually associated with “limonite” and secondary rust coloration may hide the true color.  The luster is rather dull/earthy, the streak is white, and the hardness is around 4.5. It is often porous with numerous voids and is brittle with a conchoidal fracture.  Hidalgoite is found in the oxide/secondary zone of polymetallic lead sulfide deposits.

So, it was a good day for collecting interesting minerals in the shops.