A SHOOTER OF SCHALENBLENDE; 22ND ST. SHOW; SUPERMOON

Well, this is day Number ? in home sheltering but all seems well on the virus front.  I certainly have more time to sort minerals and write for my Blog and newsletters. However, I have a great deal of concern for our medical personnel (and other essential workers) working long hours while often lacking proper equipment.  For them I am thankful. 

April snow!

I have also noticed that spring is arriving in Colorado—snow one day and 70 degrees in two days and then 32 degrees and snow in another few days.  But today is a special day as at ~7:15 P.M. the Pink Supermoon came over the horizon and the beautiful site brightened up the sky and my spirits.  A Supermoon is a fairly recent moniker given to full moons that are closer to the Earth than “normal” full moons and therefore appear larger.  Tonight’s full moon will appear about 7% larger than normal full moons and will be the largest supermoon of 2020.  The moon will not actual appear pink as that name comes from pink phlox that often blooms at about the same time as the full moon. 

No phlox blooming here at 6200+ feet although I did spot a Pasque Flower today on the slopes.  Pasque is French for Easter.  

In nations where Christianity is a major religion this full moon is known as the Paschal Moon since Easter is the first Sunday after the full moon.  Why is this particular full moon used to determine the date of Easter?  The answer is the Vernal Equinox (Latin equinoxium meaning equality between day and night), usually appearing around March 20^th.  However, this year, 2020, the Vernal Equinox appeared on March 19^th in the U.S. and was the earliest date since 1896.  The Paschal Moon is the first full moon that appears after the Vernal Equinox—in most years!  The Christian Church also keeps a lunar or Ecclesiastical Calendar that determines the exact date of Easter based upon mathematical and astronomical events that follow a 19-year cycle named the Metonic Cycle*.  In most years the Paschal Moon and the Vernal Equinox can agree on the date of Easter.  However, in some years the March full moon appears a day or two before the Equinox and that tends to foul things up.  The Christian Church then calls upon the Ecclesiastical calendar (again related to the lunar calendar) to determine the date as decided by the First Council of Nicaea in 325 CE.

As the announcer says on TV advertisements selling pots and pans—BUT WAIT THERE IS MORE.  Orthodox Christians, essentially all belonging to the Eastern Orthodox religion, celebrate Easter (and other religious holidays) based on the Julian Calendar while U.S Christians use the Gregorian calendar. Most of these Orthodox Christians live in Russia, Greece, Ethiopia, and several Eastern European countries.

BUT WAIT WAIT FOR MORE!  You might be wondering (maybe not) about a Metonic Cycle, what is it?  Merriam-Webster explains it as:

a period of 19 years after the lapse of which the phases of the moon return to a particular date in the calendar year;

a : one of the 19-year periods reckoning from June 27, 432 B.C., that were used in determining lengths of years and the placing of the intercalary month [the adding of 5 or 6 days to the calendar] in the ancient Greek calendar

b : one of the 19-year periods reckoning from 1 B.C. that are used in determining the date of Easter in the Gregorian calendar

OK, I was distracted there by the full moon but now on to minerals.  The 22^nd Street show is the largest, at least in attendance, of any venue at the Tucson shows.  In driving down I-10 near downtown it is quite easy to look east and see the giant white tents that hold the dealer booths.  The Main Tent holds about 350 dealers offering everything from beads to fossils to minerals to metaphysical magic minerals.  To the south a smaller tent handles more “upscale booths” (so they say) with floor carpeting, better climate control, and brighter lighting. A much smaller north tent has a couple of wholesale areas. 

The Main Tent at the Show.

Eurypterids, related to shrimp and lobsters were important components of Silurian faunas.  The largest of the group reached ~8 feet in length.  This specimen is about 18 inches,

A theropod (meat eating) dinosaur mounted by Rocky Mountain Resource Center, Woodland Park, Colorado.

A herbivorous horned dinosaur.

Magic rocks sold.

 One great aspect of the 22^nd Street Show is the variety of food trucks between the Main and South tents.  For the last two years I have feasted at the Curry Pot—Sir Lankan Fusion food.  Wow, yummy.   

Arizona petrified wood in the food court area.

One of my favorite buys at the entire Tucson Shows was made in the South Tent at Sokolowski Minerals from Poland. It is labeled schalenblende and is actually a variety of sphalerite (ZnS) .  The name comes from the German with schale meaning shell and blende is an old name for ore.  So, shell ore referring to the concentric banded stripes resembling agates.  Actually, schalenblende contains a variety of minerals, especially galena (lead sulfide), sphalerite (zinc sulfide), marcasite/pyrite (iron sulfide), and maybe wurtzite (zinc iron sulfide), arranged in concentric bands resembling a sliced stalagmite.

Schalenblende, a mixture of galena (G), sphalerite (S), marcasite/pyrite (M/P) and perhaps wurtzite (need XRD analysis), light cream colored sphalerite. Width FOV ~8 cm.  This is a polished surface with much light reflection.

Although schalenblende is found at many since mining locations around the world, it appears that the most attractive specimens come from Poland, especially the Silesia-Cracow District.  Two mines in the District, Olkuse-Pomorany and Trzebionka, produce most of the polished specimens seen today in rock and mineral shows.  Evidently banded schalenblende consists of several generations of sulfide minerals (as a colloid) filling pore spaces in fractures and open spaces in the forms of stalactites and dripstones (Coppola and others, 2009).  Although under debate, the schalenblende sulfide deposition (low temperature) into Triassic rooks took place in the Early Cretaceous and was related to extension tectonics associated with the opening of the northern Atlantic Ocean (Heijlen and others, 2003). 

Photomicrographs of polished schalenblende showing galena and bands of sphalerite. The different colors of sphalerite is probably due to grain size and iron content.  The heavy dark brown bands have a higher iron content. Width FOV ~ 2.8 cm. The actual specimen is much more attractive than the photos.

It is interesting to note that the Silesia-Cracow District has a mining history going back to at least the 11^th Century.  In the early 19^th century the District was producing 40% of the world’s zinc (and significant amounts of lead).  The production came from the primary galena and sphalerite and from overlying supergene concentrates of smithsonite as the most abundant mineral, but also Fe–smithsonite, hemimorphite, hydrozincite, Zn–dolomite, cerussite, goethite, anglesite, hydrous Zn- and Pb-sulfates, and phosphates.  These latter ores received the metallic elements from the oxidation of the primary sulfides (Coppola and others, 2009). But today the mining is essentially restricted to the two mines mentioned above although geologists believe that additional ore is available when the “price is right.”

 REFERENCES CITED

Coppola, V. and M. Boni, H. A. Gilg, and B. Strzelska-Smakowska, 2009, Nonsulfide zinc deposits in the Silesia–Cracow District, Southern Poland: Mineral Deposita v. 44.

Heijlen W, Muchez P,,  Banks D, Schneider J, Kucha H, and Keppens E. 2003, Carbonate-hosted Zn–Pb deposits in Upper Silesia, Poland: origin and evolution of mineralizing fluids and constraints on genetic models: Economic Geology, v. 98.