TUCSON GEM SHOW: 2015 MAIN SHOW

Today, February 12, was the opening day of the 61^st Tucson Gem & Mineral Show---the “main show”---held at the Tucson Convention Center.  The show theme for 2015, Minerals of Western Europe, brought a number of exhibitions featuring fine minerals from a variety of localities, as well as European dealers and their wares.  The following photos represent only a small portion of the many minerals in display exhibitions and dealer cases.

A Native American "Spirit Doll" with gemstone adornments.

Bowl: Brazilian agate, ca. 1970, Idar-Oberstein, Germany.

A great pyromorphite from the Las Ferges Mine, France.

A variety of specimens from localities in western Europe.

Great Norwegian silver from the famous Kongsburg District.

More silver from Kongsburg.

Mimetite from the Cumbria District, England.

Sulfur crystal from Sicily.

The star of the Show: topaz collected by Rich Fretterd (as seen on The Prospectors TV show) from pegmatites around Pike Peak.  The stone on the left is a piece of 1345.25 ct. billed as the largest faceted topaz from the USA.

More topaz from the Pikes Peak pegmatites.  For a great story, and many photos, of the topaz see www.spiriferminerals.com.

There is always gold at the Tucson Show.  This is the eight pound Thunderbolt collected from western Australia.

Beautiful rhodochrosite and fluorite from China.

Come to Arizona and see Bisbee azurite!

 

Brazilian amethyst and calcite in above three photos.  Spectacular.

The geode crackers are always popular.

I spent most of Thursday at the show and was simply overwhelmed, as usual, with the many cases and specimens.

PARGASITE: TUCSON GEMS SHOW REPORTS: WHOLESALE

The big event of the day was traveling south to the wholesale shows in south Tucson.  Most venues seem clustered around the Holiday Inn and the Kino Shows and are in the extra-large “tents.” Inside each tent the numbers of booths and tables are almost overwhelming.  Vendors are selling a wide variety of jewelry, beads, rings, cabs—you name it.  We toured through several of the tents and the displays seemed identical.  I could almost believe that the different rings etc. were all manufactured in the same factory.  I also could not observe prices that appeared to be “wholesale” in nature.  Most of the gems, cabs, silver pieces had lower prices at other venues scattered around town--or so it seemed.  So, off we went to one of my favorite shows, the 22^nd St. venue. 

 

Lots of beads.

Silver of all sorts, shapes and prices.  A great variety of chains.

From semi-precious to the big boys: rubies, diamonds, sapphires, tanzanite, etc.

Rings for everyone.  Amethyst and red garnets seemed a good buy.

I wandered through the displays back to the table featuring Pakistani minerals where previously I had purchased ruby and spinel.  I had remembered the dealer also had a green mineral for sale that was nicely perched on a white marble—similar to the ruby and spinel.  However, I would need my best negotiating skills since this green mineral was originally priced at over my $5 minimum!

I was able to purchase the mineral, pargasite, a sodium, calcium, magnesium, aluminum silicate that is a member of the amphibole/hornblende group.  The chemical formula is one that would confuse a beginning mineralogy student: [NaCa₂(Mg₄Al)Al₂Si₆O₂₂(OH)₂].  As I understand the situation, pargasite is not only a mineral but part of a “group” bearing its name. Chromio-pargasite has chromium substituting for the aluminum; in ferro-pargasite iron replaces the magnesium, fluoro-pargasite has fluorine replacing the part of hydroxyl radical, potassic-pargasite has potassium replacing the sodium. 

 

I really liked this electric green variety of pargasite from Pakistan.  The translucent specimens are fairly expensive but like the previously purchased ruby and spinel, parasgite is a colorful metamorphic mineral perched on the snow white marble.  Length pargasite ~1.0 cm.

Like most hornblende group minerals pargasite occurs as opaque, dark green to green brown, prismatic to columnar crystals with a hardness of 5-6 (Mohs).  It has a vitreous to subvitreous luster and the prismatic forms have that diamond shape cross section created by cleavage angles of ~56^o and ~124^o. 

However, there is a variety of pargasite that is an electric green color and gemmy and transparent and that is what I purchased.  This type of crystal stands out very nicely on white marble.  The specimen came from the Hunza Valley of Pakistan and was found in metamorphosed carbonate shelf limestones.

BOURNONITE: TUCSON GEM SHOW REPORT: TUCSON CITY CENTER

One of the larger show venues is the Arizona Mineral and Fossil Show centered at the Hotel Tucson City Center north of downtown.  There is a mixture of paleontological/fossil dealers (many in the Fossil Hall) but some scattered in the hotel rooms, high-end mineral dealers, numerous purveyors of nice jewelry, and a variety of smaller dealers selling all things rockhounds might be interested in purchasing.  There is a beautiful hotel courtyard pool with lunch tables scattered in the grass and paleo specimens (dinosaurs) peering at visitors.

Ammolite, a biogenic gemstone.  The ammonite is Placenticeras sp. from the Bearpaw Formation (Cretaceous).      

I enjoy the Paleo Hall as Glen Rockers from my old hometown of Ha in Alberta, Canada.ys, Kansas, always displays a number of fine Cretaceous specimens from the western Kansas chalk beds.  One of my past blogs discussed a fantastic specimen of amber, known locally as Jelenite, from the Dakota Formation (Cretaceous) in central Kansas (9/232012) .  Another specimen is a full-body mount of nice bill fish called Protosphyraena.  He told me that the specimen is about 80% complete, including the skull.  During my time playing in the chalk collectors often found the rostrum (the bill) that had broken from an unknown skull.  In viewing the photo below remember that the rostrum actually supported a ?cartilaginous covering.  The famed fossil collector Charles H. Sternberg postulated in 1917 that the front teeth projected in a forward direction and the bill and teeth were used as a ramming device on other fish or mosasaurs.  I think paleontologists remain uncertain about the use of the bill and teeth; however, Sternberg seemed correct about the projecting teeth.

Protosphyraena, a bill fish from the Cretaceous rocks of western Kansas.  Collected by Glen Rockers.

I was able to locate my mineral of the day for $4, bournonite [PbCuSbS₃], a lead copper, antimony sulfide (sometimes containing arsenic).  The crystals have a metallic luster and usually a steel gray (metallic) color.  Bournonite is a rather soft mineral, ~3 (Mohs), opaque, and sometimes fractures in subchonidal surfaces. The crystals of bournonite are usually short prismatic in nature and are deeply striated. They often form twins that repeat and then form “cogwheels” that resemble deeply striated hexagonal or cubic crystals.  In other instances the crystals are tabular, or even massive.  The twinned crystals seemed to be the best way to identify bournonite from similar looking enargite [Cu₃AsS₄].  Bournonite is the result of hydrothermal solutions and often associated with ore minerals such as galena (lead), tetrahedrite (copper/silver) and sphalerite (zinc). 

Older references, especially from England, often refer to bournonite as "wheel ore" due to its repeated twinning producing "cog wheels."  My specimen was collected at the Quiruvilca Mine (La Libertad Mine; ASARCO Mine), Quiruvilca District, Peru. According to MinDat.org the mine is "a copper-lead-zinc-silver-gold mine owned by ASARCO (80%)."  MinDat lists 37 valid minerals collected from the mine.
  

Bournonite.  Notice the two larger twinned crystals with deep reenterant grooves.  Length of upper large crystal ~6 mm.

Repeating crystals of bournonite forms a "cogwheel."  Figure courtesy of www.smorf.nl/ via www.minerals.net.

Dark silver-gray colored (metallic) bournonite.  Width of photo ~4 cm.

So, it was another successful day of admiring minerals, fossils and hunting for “cheap” mineral specimens.