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.

NEWS FROM TUCSON; 2020 SHOWS HAVE STARTED

The time has come—Tucson 2020.  According to advertisements there are 51 different show venues this year with the culminating Tucson Gem and Mineral Show®, the main show, running February 13-16 at the Convention Center downtown. Smaller shows “officially” started Saturday January 31 although my dealer friends tell me that high end trading and buying in hotel rooms started much earlier.  In fact, some collectors of fine minerals had left town by February 1.  However, I am just an ole rockhound from Colorado Springs and happy to be here in the sunshine talking to the friendly, often mom and pop, dealers, and frugally buying a few goodies that light up my eyes.  Life is good.

After arriving in town, I started my wandering on Monday the 3^rd and was able to hit a couple of venues in the afternoon.  My worn-out legs will simply not allow me to wander aimlessly so I pick my shows carefully where some of my favorite dealers reside, and where I am able to see some interesting specimens.

There are 1 million, 497 thousand and 642 carved Moroccan Orthoceras cephalopods for sale at the various Tucson venues.  They are only exceeded in number by strings of "beads" (below).

Although I am not into collecting fossils at this stage in my life, I enjoy seeing nice  vertebrates (clones) and invertebrates collected from private lands.  The molding and casting processes get better each year, and the prep work on some of the invertebrates is fantastic.  I generally stay away from Moroccan fossils since so many of them are repaired, carved and painted, and are simply unauthentic.

Small fish from the Green River formation in western Wyoming (Eocene) dwarfed by a large Xiphactinus from the Smoky Hill Chalk (Cretaceous) of western Kansas.

Marine reptile from Morocco. Is it "real"?  Don't know as I did not examine closely.  I do know that Mosasaur "jaws" complete with a row of teeth are for sale everywhere in the shows.  Most are composites.

One of the nifty places to see nice fossils and clones is the Mineral and Fossil Marketplace on North Oracle. Leon Theisen of Custom Paleo out of Ardmore, Oklahoma, has a fantastic collection of Devonian and Ordovician invertebrates collected from his two privately owned quarries.  He also has a magnificent amber barite from the Pierre Shale along Elk Creek that he collected several years ago (see my previous post on the barite).  He is always willing to spend time with visitors spinning a yarn or two.

Minerals and rocks by the flat, bucket or individuals are "for sale" by the "mom& Pop dealers.  Many have very nice specimens for the buyer.

Next door to the fossils are several “mom & pop” booths selling a variety of minerals.  At the time I visited, the vendors were trying to tie down and protect their tents from being destroyed by a nasty wind.  I also missed Jack Crawford at his usual spot. Jack, formally from Colorado but now from Silver City, New Mexico, was a great source of information on Baja minerals and always willing to share information.  His neighbor said he evidently sold his business and moved on. 

Trilobite from Custom Paleo in Oklahoma.

Down (south) Oracle a half block is an amazing store called Superb Minerals, 12,500 sq.ft. of the nicest zeolites one can observe—anywhere.  These minerals are from the Deccan Plateau in India and are found in concretions, GIANT concretions.  One can purchase Indian zeolites in about any rock shop or show and different minerals are very showy and quite reasonable in price.  However, these concretions are spectacular, and some could set you back $75,000 or more.  But they are nice. 

Zeolites and more zeolites.

The above three photos show the giant concretions containing a variety of zeolite minerals.  The floodlight is approximately 6 inches in diameter.

So, what was I able to snatch at the mineral booths? For starters I shelled out a whole two bucks for some small wulfenite crystals.  A lead molybdate [Pb(MoO₄)], wulfenite is famous for its common habit of forming thin tabular crystals, often transparent (but ranging to opaque), that occur in various shades of orange to red to yellow (uncommon as green or brown or blueish or black) and “butterscotch” is a common color descriptor.  Wulfenite is Loved was the theme of the 2019 Show so why pick some a specimen this year?  The main reason is that the specimen was collected from the Old Yuma Mine, a polymetallic producer not located near the town of Yuma, Arizona, but situated just on the west outskirts of Tucson in the volcanic Tucson Mountains.  The Mine operated, sporadically, between 1916 and 1947 but was never a large metal producer; however, it did yield spectacular specimens of wulfenite and vanadinite.  Notice I used the past tense “did yield” since it was gobbled up by Saguaro National Monument, and since collecting is not allowed on USNPS lands, there will no longer be “fresh” Old Yuma Mine specimens floating around.  I just want to have a specimen from that rather famous locality.

Blades of wulfenite from Old Yuma Mine.  Width FOV ~1.4 cm.

For the same reason, I just want it, another two bucks bought me a crystal of idocrase (AKA vesuvianite) from the Fushan Mine in Hebei Province, China. Vesuvianite has a very complex, at least for me to understand, chemical formula and interestingly contains both neosilicate (SiO₄ with a silicon anion and one tetrahedron) and sorosilicate (Si₂O₇ with two tetrahedra) groups:  Ca₁₀(Mg, Fe)₂Al₄(SiO₄)₅(Si₂O₇)₂(OH)_4.   The nicest specimens (and I have not seen many) that I have observed are green in color, but specimens also might be brown to yellow to even a nice blue-purple in color.  If in crystals, they are usually prismatic and “eight-sided” with one set (of sides) being quite dominant so the prisms look square in cross section.  They are commonly terminated with a four-sided pyramid.  Vesuvianite is a fairly hard mineral at ~6.5 (Moh’s) with a vitreous to “greasy” luster.  Gemmy vesuvianite is transparent to translucent while other specimens are less than translucent (not quite opaque but something).

Tough to get good photos of a greenish termination of a "squat" vesuvianite crystal. The termination is a four sided pyramid with a flat top.  The numbers represent Miller Indices and are included to better observe the crystal faces.  In the center of the flat top is Axis C running "down" through the crystal.  The A and B axes run from side to side.  The "square looking" crystal is ~1.8 cm in size.

There were a few other purchases, but descriptions will come later.