DENVER FALL 2020 MINERAL AND FOSSIL SHOW

 I am no longer a curmudgeon. I am a curmudgeon emeritus.  

                    James Gibbons

Our interesting year continues.  And in my case continues day after day after day as I essentially self-quarantine at home. I am tired of yard work, miss my daily coffee shop meetings with friends, miss camping (Colorado sites are packed), wish for resumption of club and mineral group meetings, and regret my knees will not take bending and walking to collecting sites.  I also greatly regret that science is taking a terrible beating in Washington and in some of the national news media. The future of our nation, and in fact the planet, depends upon “real” research and listening to the advice of scientists.  Our children and grandchildren are going to inherit a planet that will reflect the sins of the current generation.  And, as the beating goes on and on, who will want to become a STEM major in higher education, or who will want to believe the opinion of scientists?  For me, it is a disturbing situation and I regret the lack of a magic wand to correct and make positive changes for humanity.

The easy path of aging is to become a thick-skinned, unbudging curmudgeon, a battle-ax. To grow soft and sweet is the harder way.

                          James Hillman

I keep telling myself to wait, things will get better, stay healthy, and remember the rainbows arrive after the storm.  Well, speaking of rainbows Charlie Chaplin noted that “you'll never find rainbows, if you're looking down.”  So, I decided to look up and what did I spot, the 2020 abbreviated version of the Colorado Mineral and Fossil Fall Show—a rainbow!  Now the question arises of sneaking up to the Show, or being safe and staying home (as my children would prefer). In fact, a second decision involved attending the Fall Show at the Crowne Plaza Hotel (Sept. 11-15) or the Denver Expo Gem Show and the Denver Show, both at the National Western Complex (Sept. 11-21).  Which would it be?  I am still quite spooked about COVID-19 so picked the smaller Show at the Crown Plaza and decided to forego the much larger Denver Western Complex shows with a larger number of people.  It was a good decision.

So off I went for a day’s visit to Denver and an escape from yard work and the ho hum of the self-quarantine.  I had my mask (actually three), hand sanitizer, and the smarts to work with social distancing protocols.  It tuned out to be a great day with limited attendance, lots of big hand sanitizer bottles scattered around, and dealer tables spaced far apart with no jostling of buyers.  In addition, I had several informative visits with dealers only too happy to have customers—I mean listening to Dennis Beals spin yarns about collecting garnets south of the border is classic.

Upon entering the building at a few minutes before opening time I was warming greeted by informative “guides” who pointed out the numerous showrooms available for perusal by the general public.  As usual, I tried to sneak into the wholesale room just to see the specimens but was detained by a nice security person.  Too bad as the tables looked nice. 

The ballrooms were large and tables widely spaced.  Some had sneeze guards installed.  Bottles of hand sanitizers were scattered around the rooms.
 

Murph's Petrified Wood had a nice collection of polished slabs, mostly international in origin.

The centerpiece of Murph's collection, noted in the center in above photo, was a slab from Indonesia. 

A little out of my price range but a beautiful, museum quality, specimen of brochantite (hydrous copper sulfate) crystals from the famous Milpillas Mine in Sonora, Mexico..

Way out of my price range at $20k; however, Kristalle from Laguna Beach, CA, always has beautiful specimens including this brazilianite (hydrous sodium aluminum phosphate) from Brazil.

 

Everyone likes gold, especially specimens shown by Kristalle.

One of my favorite minerals, variscite, the rare hydrated aluminum phosphate collected from Clay Canyon, UT.  Variscite is green while the lighter yellow-like material is probable crandillite (another phosphate).

Dennis Beals from XTAL in Denver always has a nice selection of minerals (very reasonable prices) and yarns.

Blue hemimorphite (hydrated zinc silicate) from the Ojuela Mine, Durango, Mexico. Is this the real color of hemimorphite? 

Few fossils were available but these Moroccan shark's teeth and invertebrates were scattered among selenite crystal lamps, small spheres, a cephalopod bowl, and some other "stuff."  

Utah Tiffany Stone (Trade Name) mined for beryllium at Spoor Mountain in the West Desert of Utah.  These nodules were originally carbonate clasts, then replaced by purple fluorite which was then replaced by opal and/or chalcedony.  Microscopic grains of bertrandite (hydrous beryllium silicate) in the fluorite provide the beryllium available for mining by Brush Wellman.  
 

There was even an Estate Sale offering minerals.

The main emphasis of the sale were specimens of native gold and silver; however, there were other minerals available for purchase.

Outside of the hotel there were a few scattered tents and the Covid-19 protocols were tight.
 

And how could a show not have a display of amethyst cathedrals? 

Albert Einstein said, we act as though comfort and luxury were the chief requirements of life. All that we need to make us happy is something to be enthusiastic about. I would add that a good old-fashioned rock and mineral show makes any ole rockhound happy in the time of Covid.

 

ANAPAITE: NOTHING TO WRITE HOME TO MOMMA ABOUT

 

I was rummaging around in my drawers of minerals attempting to kill some time and trying not to feel sorry for being self-quarantined when I stumbled on an older looking perky box labeled anapaite.  A “long time” ago I had checked on this mineral after purchase and had written “phosphate” on a label. OK, so what was it?  The collecting locality was “Cerdanya, Catalonia Spain.”  That must be a nice place to visit came into my mind so I decided to check it out, not that I will ever make it to Spain.  I only knew a few insignificant “facts” about Catalonia: 1) Catalans are trying to win independence from Spain and speak the Catalan language; 2) Barcelona is the second largest city in Spain and is a major tourist destination on the Mediterranean; 3) Salvador Dali was a Catalan; 4) the northeastern part of Catalonia contains the Eastern Pyrenees, part of the Pyrenees Mountains, running east-west and forming the border between Spain and France—sort of.  The Principality of Andorra, a microstate of ~180 sq. miles, is stuffed in along the border as the official boundary splits to accommodate this tiny area.  As a kid I was a geography freak (still am) and studied intensely every map I could lay my hands on (not many in my small Kansas community).  Places like Andorra I could only imagine in my daydreams but did manage to nab some Andorran stamps with “pretty pictures.”  

Tectonic map of southern Europe, North Africa and the Middle

East, showing tectonic structures of the western Alpine 

Mountain Belt.  The Himalayan Mountain Belt continues to the

east off the map. Map Public Domain credited to Woudloper.

So, as I was learning about the mineral anapaite, I was also learning about the geology of the Pyrenees Mountains—who said I could not multitask?  The current configuration of the Pyrenees Mountains is related to the collision of the Iberian (Spain and Portugal) Plate and the Eurasian Plate in the later Cretaceous and early Tertiary.  The Iberian Plate was subducted by the overriding Eurasian Plate creating numerous faults and compressional structures as the once independent Iberian Plate was being squeezed between Africa and Europe.  In fact, the Pyrenees represent the western edge of the ~8000 miles long Himalayan-Alpine Belt that formed as a result of collisional dynamics between Arabia, India, Asia, and Europe—plates were on the move!

Sketch showing Eurasian Plate overriding Iberian Plate during the early Tertiary.

However, the Pyrenees’ collision dynamics were unlike the tectonic activity in the Himalayan and Alps mountains.   In the latter system, where continental plates with low densities collide, they do not subduct beneath each other, at least not much. But the crust does shorten, as the margins of the two colliding continents together with whatever was between them get scrunched together into huge folds and uplifts.  That collusion describes the Himalayan and Alps mountain zones (Gibson, 2014). However, the Pyrenees were not generated by a continent to continent collision, but merely reflect the confrontation of two distended but continuous continental domains during the Tertiary, leading to the incipient underthrusting of the Iberian crust under the European crust (Canerot, 2016).

Continent to Continent plate collision with crustal shortening causing rising elevation. Public Domain map with credit to U. S. Geological Survey.

In the later Tertiary (Miocene) several structural basins formed (probably due to extensional tectonics and faulting) within, and adjacent to, the Pyrenees including the Cerdanya Basin where several hundred feet of lacustrine (lake) sediment accumulated as organic ooze and diatomite (composed of fossilized diatoms which are microalgae). Within these lake rocks geologists located phosphate minerals, mostly anapaite and fairfieldite, in veins, nodules and spherulite beds.  These phosphatized sedimentary rocks are diagenetic in nature (alteration of existing minerals by chemical change) and very dependent on environmental conditions of deposition and are quite different from phosphate minerals described from marine systems (De las Heras and others, 1989). In marine units, phosphorus accumulation occurs from atmospheric precipitation, dust, glacial runoff, cosmic activity, underground hydrothermal volcanic activity, and deposition of organic material. The primary inflow of dissolved phosphorus is from continental weathering, brought out by rivers to the ocean (Delaney, 1998). 

Location of Cerdanya Basin along axis of Pyrenees Mountain.  Map from Lewis and others, 2000.

Almost all igneous rocks also contain a phosphate mineral and it is almost always an apatite group mineral that forms as an accessory mineral.  Again, the accumulation of igneous phosphatic mineral is much different than marine or lacustrine phosphates. When apatites occur as accessory minerals in igneous rocks they are of macroscopic size and are idiomorphic (identifying crystal form). These are generally fluorapatites which are relatively rich in CI and are characterized by high contents of trace elements. By contrast, apatites formed in surface environments are usually sub-microscopic and are barely visible. These latter apatites are usually carbonate fluorapatite in sediments, or hydroxyapatite in vertebrate skeletons (Lucas and others, 1997).   

Anapaite [Ca₂Fe(PO₄)₂-4H₂O] is an interesting mineral—for a number of reasons: 1) at the type locality in Anapa, Russia (Crimean Peninsula and formally in Ukraine), it is found in the stems of fossil trees and in phosphate bearing, oolitic iron ore; 2) the mineral occurs in two different crystalline forms—bladed/tabular, and spiky; 3) it is commonly found in rosettes, crust-like subparallel aggregates, in geode-like nodules, and fibers.  

Photomicrographs of green to gray-green anapaite in veins of matrix that may be an apatite group mineral. All crystals are sub millimeter in size.

Anapaite is often green in color but ranges to greenish white, gray-green and colorless.  It has a vitreous luster, a white streak, and is somewhat soft at ~3.5 (Mohs), and transparent. It is not a “write home to momma” mineral but is interesting due to its formation in a freshwater lake.

Early 1930s French postage stamp overprinted for use in Andorra.

REFERENCES CITED

Canérot, J., 2016, The Iberian Plate: myth or reality?: Boletín Geológico y Minero, vol. 127, No. 2/3.

Delaney, M.L., 1998, Phosphorus accumulation in marine sediments and oceanic phosphorus cycle: Biogeochemical Cycles, vol.12, no. 4.

De las Heras, X., J.O.Grimalt, J.Albaigés, R.Juliá, and P.Anadon, 1989, Origin and diagenesis of the organic matter in Miocene freshwater lacustrine phosphates (Cerdanya Basin, Eastern Pyrenees): Organic Geochemistry, vol. 14, issue 6.

Gibson, R., 2014, Alpine-Himalayan Orogeny http://historyoftheearthcalendar.blogspot.com

Lewis, C.J., S.J. Verge, and M. Marzo, 2000. High mountains in a zone of extended crust: insights into the Neogene – Quaternary topographic development of northeastern Iberia: Tectonics vol. 19, no. 1.

Lucas J., Prevot-Lucas L. 1997, On the genesis of sedimentary apatite and phosphate-rich sediments, In H. Paquet and N. Clauer: Soils and Sediments, Springer, Berlin, Heidelberg.