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,