BLUE AFGAHNITE: TUCSON 2016

The 22^nd Street Show is one that I attend every year as it offers something for everyone!  The event is held inside of a giant tent (or so they say) anchored on a concrete floor.  Like most of the ancillary shows the parking lot is gravel and a tremendous amount of dust greets visitors upon arrival,  When I first attended the Show several years ago a hot dog was about the best one could do for lunch.  Today the food trucks have found the location and a variety of decent food is available.  The 22^nd Street location is also the building where many of “The Prospectors”  of TV “fame” hang out and sell their wares.  There seems to be a big market for signed posters and selfies with one of the celebrities!

Prospector Amanda at her booth.

How this stylized human figure composed of metal relates to rocks, minerals and fossils is beyond my realm of thinking. 

You name it; you take it home.

A wash basin for all with lots of partial cephalopods direct from Morocco.  I have often wondered how many cephalopods have been collected from Morocco??  

Item in abundance at 22^nd Street include a variety of fossils, especially large vertebrates.  Although illegal to collect from Federal lands in the U.S., the vertebrate fossils on display were collected, I presume, from private lands.

Last year I purchased several specimens of red spinel and ruby from a Pakistani dealer, and had some very nice conversations.  This year that particular dealer was absent, as was another dealer who always had several tables of minerals and crystals.  Instead the tent is increasingly being populated by some rather ecletic items of little interest to me.

However, I was able to hunt through some mineral tables and pick up a specimen of afganite, another one of those $5 minerals that displays a nice bright blue color and is rather uncommon in collections.  I felt fortunate in being able to ferret out this sample.

Fossil fish on a slab collected from the Eocene Green River Formation from near Kemmerer, Wyoming in the western part of the state.  If readers are ever in that area be certain to visit Fossil Butte National Monument.  The fish have been enhanced with a dark ink in order to provide a “better” display since these are objects de art rather than museum specimens.

A very nice reproduction of the Cretaceous carnivore Albertosaurus offered for sale by Tribold Paleontology over in Woodland Park, Colorado.  

An impressive reproduction of Torvosaurus, a large carnivore from the Jurassic Morrison Formation (Skull Creek Quarry, private) near Dinosaur, Colorado.

This is a lower jaw of a very young mastodon collected from the La Brea Tar Pits of California.  It must be an old specimen (20^th Century) since it is fairly impossible to get an actual specimen out of the preserve today.  Perhaps it came from a trade with some of the earlier paleontologists?

Skull of Basilosaurus, an Eocene whale from Morocco.  To early paleontologists it looked like a reptile hence the saurus moniker.  However, it actually in a mammal.  I did not check on the percent of reconstruction!

Afgahnite is a sodium, potassium, calcarous alumosilicate with a very complicated chemical formula: (Na,K)₂₂Ca₁₀(Si₂₄Al₂₄O₉₆)(SO₄)6Cl₆ .  It usually is a striking blue in color but at times the mineral is white, as is the streak.  Afghanite has a medium hardness of ~5.5-6.0 (Mohs) with a vitreous luster and a translucent to transparent diaphaneity.  It has a conchoidal fracture as occurs as massive blue material with scattered crystals (hexagonal system).  For example, the photos on MinDat are almost always nice doubly terminated dipyramidal crystals while my specimens only has the faintest outline of crystals. It is, or is related to, the feldspathoids, a group of minerals with a low silica content that are not found in rocks containing primary quartz.  My specimen has a matrix of metamorphic marble as do most of the specimens from the primary locality where the host rock is a skarn zone (where a limestone has neen intruded and cooked) in an Archean (Precambrian) gneiss and schist: Ladjuar Medam (Lajur Madan; Lapis-lazuli Mine; Lapis-lazuli deposit), Sar-e Sang (Sar Sang; Sary Sang), Koksha Valley (Kokscha Valley; Kokcha Valley), Khash & Kuran Wa Munjan Districts, Badakhshan Province (Badakshan Province; Badahsan Province), Afghanistan  Location from MinDat.

Photomicrograph of massive afghanite along with a cross section of a crystal noted by the arrow.  FOV ~1.6 cm.

Massive afghanite on matrix with arrow pointing to a crystal cross section shown in photomicrograph above.  FOV ~3.5 cm.