BLUE CAVANSITE; ZEOLITES: TUCSON 2016

Today was another short day on the observing/collecting trail.  In the last post I lamented about participating in dump day, a necessary but “not so fun” time---my least favorite day of the week.  Today is my second least favorite day, but one that is much more appealing to the sensory organs—laundry day!  This particular event always returns me, at least in my mind, to this dreaded day during my college years.  To be honest, I was terrified the first few times when entering a self-service laundromat, absolutely scared to death. Some of that fear continues today. 

Before leaving for the freshman year in college my mother tried to show me a few tips on the home washing machine about this entire ordeal; however, most of her information just did not take with me.  And, her machine was unlike anything I later observed in the laundromat.  Living in the residence hall (a dorm back in the old days) I tried to be very frugal with my clothes usage.  However, the day finally came on a Saturday—my roommate, also terrified of the monsters, suggested that we head out to wash our clothes.  Perhaps he was unsatisfied with my cleanliness, perhaps he was just running out of wearable material.  At any rate, off we went hoping to avoid meeting any females in the laundromat.  We assumed that females knew all about the washing process and we were greenhorns and did not want to show our lack of intelligence about certain items.  And besides, if members of the opposite sex were around we surly would need to sort of hide our “white clothes.”

Well, we picked the wrong time of the day for our little chore since most of the machines were busy, and several college coeds were present and seemly starring at us as we entered the dreaded building and put our claim to three washing machines.  My roomie just dumped his bag, containing all sorts of colors and whites, into the same machine.  At least I knew enough to stuff the colored material into one machine while sneaking the whites into another washer.  The next question revolved around how much soap should we use?  We had purchased a large bottle of the cheapest laundry soap we could find at the store. My buddy came to the conclusion that since we had cheap soap then more was better.  The machines were “top loaders” so we poured in a generous amount, and then added a little more.  We set the little button on “hot,” inserted the coins and stepped back with a smug look on our face---we had challenged the monsters and won, nothing to it---WRONG.  Big way wrong.  As the machine filled and the agitator began to whirl back and forth we noticed frothy bubbles creeping out of the void around the lid, something like a rabid dog. A few seconds later the bubbles turned into something like a volcano, pouring out of the machine and heading to the floor. The monsters were unleashed—who let the dogs out? Wow, what could we do as the machines would not shut down!  Could we pull the plugs and dip out the suds?  No, as the cords were hard-wired.  Our faces grew very red as we grabbed for a mop and spent the rest of the wash cycle trying to stem the river of soapy water.  The coeds, at least in our minds, were laughing their heads off at two guys from the sticks.

That little episode in the laundromat scared me forever and I still break into a cold sweat whenever I smell that particular odor coming out of a building.  Here in Arizona, laundry day simply means getting a later start on tackling some of life’s persistent questions.  However, I am pretty certain that laundromats left a vivid impression on many males of my generation.

Every year on a short day I try to visit a building on Oracle Street that specializes in zeolites from India.  This venue has the most amazing collections of zeolite minerals, several of which are museum-quality specimens.  I head to this store, not to purchase, but to observe the displays of minerals collected from the basalt on the Deccan Plateau.  The Deccan Traps, as the basalt is known, has produced some of the finest zeolite specimens in the world.  At virtually any rock or mineral show there are literally hundreds/thousands of Deccan zeolites for sale.  The encasing basalt was extruded somewhere around 65-66 Ma, right at the end of the Cretaceous.  Today the volcanic hotspot may lie under the Indian Ocean island of Reunion.  As crustal plates associated with the modern country of India passed over the hotspot on its way north to collide with parts of Asia (producing the Himalaya Mountains) vast quantities of basalt reached the surface.  And these basalt layers are rich in zeolites, a varied group of aluminosilicate minerals. 

 

A fine specimen of scolecite exhibiting several sprays of elongated and acicular crystals.  Height ~25 cm.

A large vug containing zeolite crystals, probably stilbite/stellerite and others.  This is a very large “concretion” perhaps 1.2 M in length.

Stalagmitic stilbite (I think) about ~30 cm in height.

Sprays of mesolite (I think) sitting on top of another zeolite, perhaps stilbite/stellerite.  These sprays are ~15 cm. high.

A really giant vug (notice lamp) exposing at least two different zeolites (stilbite/stellerite and others) in the center.  This “concretion” is ~152 cm in length.

I previously offered postings on a few zeolites such as those collected at Table Mountain in Golden, Colorado, the thomsonite nodules from Lake Superior and mordenite from the western US.  However, identification of individual species from this large group (~90) of minerals still confuses and sort of frightens me—sort of like entering a laundromat! 

 

So, what does one purchase while looking at Indian zeolites?  The obvious answer this year would be blue cavansite, a hydrated calcium vanadium silicate Ca(VO)SiO₄O₁₀-4(H₂O) (and I purchased three specimens).  One in my collection is a nice specimen of stilbite crystals (may be stellerite) perched on a base of heulandite, both are zeolites, with a dainty spray of tiny blue crystals perched on the stilbite. The record of discovery goes to the basalts cropping out in Malheur County, Oregon, but today most collector specimens come from India.  I suppose that I may have missed cavansite in Mineralogy class since it was not reported in the literature until 1967!

Cavansite spray perched on stilbite/stellerite with a base of heulandite.  Width of entire specimen ~5.5 cm while width of spray ~7.5 mm. top is a photo while bottom is a photomicrograph.

Cavansite usually appears as radiating sprays, or balls, of prismatic dipyramidal crystals (Orthorhombic System), blue in color, soft (3-4 Mohs), and with a vitreous luster. Cavansite is a secondary mineral (probably low temperature) found in vugs of basalt. It usually occurs with zeolite minerals but is not chemically related to that group. It has a paramorph termed pentagonite (same chemical formula and color but with bladed crystals) that seems to be a high temperature form.

So, although the day was short I saw some beautiful and spectacular zeolites and even made a frugal purchase of some nice blue minerals.

WHY IS THE SKY BLUE:  A clear cloudless day-time sky is blue because molecules in the air scatter blue light from the sun more than they scatter red light.  When we look towards the sun at sunset, we see red and orange colors because the blue light has been scattered out and away from the line of sight... Blue is the color between violet and green on the optical spectrum of visible light,      Human eyes perceive blue when observing light with a wavelength between 450 and 495 nanometres.
              From Dept. of Physics, University of Riverside, California,

BLUE CHALCEDONY: TUCSON 2016

My second day of the Tucson journey was spent at the Moroccan Dealers Village on North Oracle Street.  It was a short visit day due to an important event at the State Park campground---a day know affectionately to all RV campers as “dump day!”  In my situation, this event requires moving and securing all items in the RV, closing up the slide rooms, hooking up the unit, and then slowing proceeding to the campground “dump station.”  Grab your gloves, hook up the drain hoses, back away from the “little hole to the campground's main sewer” and pull the drain plugs on the RV---and hope there is no splashing, or in the worst case scenario I have observed, having the drain hoses come loose from the RV.  Dump day is the equalizing activity for all RV campers---big ones, middle ones and small ones, hundreds of thousands of dollars to a few hundred dollars---they all need the black tanks emptied at some point!

 

The tents at the Moroccan Dealers’ Village covered nearly two lengths of city blocks.

I like to refer to these pieces of sculpted quartz as Washington Monuments.  Perhaps they are ordinary obelisks, or mystic towers.  Perhaps they are just pieces of carved quartz for designer coffee table.  Whatever, there were numerous specimens of all sizes scattered throughout the Shows.

A nice slab of Paleozoic crinoids but with much reconstruction.

Fossils are always a mainstay at Moroccan dealers.  These coiled cephalopods are saucer-size and relatively cheap.

Talk about reconstruction, not only are many of these cephalopods carved and built, they are “glued” onto the matrix.  Built for designer homes of non-rockhounds.

How many shark’s teeth does it take to fill a large flat?  I don’t have the slightest idea!

Most specimens for sale from the Moroccan dealers were either: 1) very large slabs of fossils such as the crinoids and cephalopods shown above; or 2) flats of smaller fossils (see shark teeth).  Several U.S. shop dealers were visiting the Moroccans and negotiating for large purchases; $100 bills were certainly changing hands.  I hunted through the boxes but found little of interest.  So, across the street I went---back to my Day 1 haunts (see previous posting) where I hunted through the boxes and located blue chalcedony.

 

Blue vein chalcedony from the White River Group, South Dakota.  Width of vein ~2.3 cm.

So, why would I want to buy three pieces ($2 for all three) of blue cryptocrystalline quartz?  The answer is simple, but maybe hard to explain!  I have written several postings about collecting rocks and minerals in western South Dakota, the scene of my field work for the graduate masters degree.  Today most of these degrees in science are MS Degrees (Masters of Science); however, mine was actually an AM Degree (Masters of Arts).  I don’t have the slightest idea the reason behind this little quirk.

At any rate, I wandered over countless acres of rocks described as either the Brule Formation or the Chadron Formation and collectively known then as the White River Group.  If readers have ever visited Badlands National Park, they have seen the units with an amazing fossil biota.  In addition, some of the rocks are crisscrossed by sedimentary dikes--most are clastic dikes composed of sandstone while others are dikes of blue to lavender chalcedony.  I remember picking up numerous specimens during my field work but over the years tumbled and/or gave away these beautiful pieces of chalcedony.  The blue chalcedony is easy to recognize and I have been rummaging around for cheap specimens for several years.  And, here they were in a labeled broken old specimen box and mine for the taking (actually purchasing).  Ah, my mind immediately returned to the summer of 1966 and I could hear “The Troggs” belting out the Number 1 hit of July---Wild Thing.  All adults of a certain generation know the lyrics by heart---you know: Wild thing you make my heart sing, you make everything groovy, wild thing. Come on, sing along with me!

The chalcedony veins, along with the sedimentary clastic dikes, occur at several different horizons within the Eocene-Oligocene White River Group and probably formed by a secondary processes termed diagenesis. Gries (1996) believed the chalcedony veins formed from secondary silica gel inserted into shrinkage cracks forming in the clay-rich sedimentary beds.  It appears that Native Americans utilized the chalcedony and I have recognized the mineral in projectile points.

Chalcedony is not really a separate mineral but is a variety of cryptocrystalline silica containing microscopic or submicroscopic fibers of a mixture of quartz (Trigonal Crystal System) and another silica mineral called moganite (Monoclinic Mineral System).  Over periods of time the unstable moganite converts to quartz.  I am uncertain about the age of the oldest mogenite---another one of life's persistent questions! 

Chalcedony, that seeming common “mineral” found in all sorts of sedimentary rocks in both primary and secondary environments, and sometimes in igneous and metamorphic rocks, is actually quite complex.  For an in-depth discussion, including length-slow vs. length-fast chalcedony, see the quartz page at:  www.quartzpage.de/chalcedony.html.

For an ole rockhound like me chalcedony is fairly easy to recognize due to its waxy luster becoming vitreous when polished, hardness (~6.5-7.0 Mohs), conchoidal fracture, its habits of forming mammillary masses, vein fillings (as in the Badlands) stalagmitic masses, “blobs” in geodes, or just weathered out pebbles and cobbles of waxy looking quartz.  Chalcedony is translucent and never quite transparent or opaque.  Sometimes the “mineral” is the cementing agent in sandstone or the permineralization/replacement agent in fossilized (petrified) wood.

   

As for the blue color, The Quartz Page notes “The blue tones…found in pure chalcedony are caused by Rayleigh scattering [too lengthy and difficult to explain here.  If interested I would suggest further research and reading] of light on tiny particles, the mechanism that is also mostly responsible for the blue color of the sky.”

One other thing—chalcedony, as well as agate and other varieties of microcrystalline quartz, are porous and easily dyed.  Know your dealers, ask questions, and if it looks too colorful to be real, then it probably is a "fake"!