BLUE SERPIERITE: TUCSON 2016

Now, when I finally found the Colorado Springs group I had forgotten my camera.  So, I have substituted some beautiful Mexican Gold Poppies blooming in the desert.  They are a spring delight.

My next journey was to visit the displays of the Miners Coop Rock Show.  I had been hunting several days for the vendors as the show venue moved from the 2015 location.  Of course I never bothered to examine one of the Show booklets to locate a position; however, even the booklet had a wrong listed location!  At any rate I found them on the west side of I-10 near the Ina Exit.  I was particularly interested in this group since at least three vendors were members of the Colorado Springs Mineralogical Society (CSMS).  In addition, a business from Arkansas and another from Gardner, Colorado, were present with their booths.  These latter two are regular vendors at our June CSMS event.  After visiting with the CSMS members, I diligently hunted through other displays and came up with up a couple of nice blue specimens of a calcium copper zinc sulfide known as serpierite [Ca(Cu,Zn)₄(SO₄)₂(OH)₆-3H2)].

Serpierite is another one of those nice blue copper minerals ranging from a light to a dark sky blue with some almost a blue-green turquoise color. It occurs in fluffy tufts, crusts, or aggregates of very tiny, lath-like vitreous crystals.  These small crystals are transparent and some almost lack color.  They are somewhat confusing, at least to a soft rocker like me, in that the crystals are elongated along axis a and not the “usual” c axis.  In fact, they are flattened along the c axis to produce the lath-like shape.  Serpierite fractures easily into splinters and seems quite soft (~2 Mohs).  I tried an unglazed porcelain plate and the mineral essentially leaves a white streak.

Serpierite is a member of the small Devilline Group. I have a small specimen of devilline [CaCu₄(SO₄)(OH)₆-3H₂O] where the small tuft of platy crystals are essentially impossible for me to distinguish from serpierite.  As one can observe devilline is missing the zinc of serpierite.  Add some cadmium in place of some of the calcium in serpierite and the mineral becomes aldridgeite (structure the same: isostructural). 

Serpierite is a secondary mineral and found in the hydrothermal zone associated with copper and zinc deposits.  For example, at the type locality of serpierite in the Lavrion District of Greece, there are numerous primary copper minerals and primary zinc minerals such as sphalerite.

 

I have three specimens of serpierite from different localities and all are somewhat different: Lavrion District, Greece; Creole Mine, Beaver County, Utah; Bay Horse District, Challis, Custer County, Idaho.

Photomicrograph of serpierite collected from its type locality at the Serpieri Mine, Lavrion District, Greece.  Width FOV ~3 mm.

The Lavrion District of southeastern Greece is probably the country’s most famous and oldest mining area.  There are signs copper was mined in the years 3000 B.C—2000 B.C. corresponding to the Early and Middle Bronze Age.  Of interest is that copper, along with tin, is the major component of bronze.  In 483 B.C. large deposits of silver were discovered and these mines had a direct and major effect on the creation of the Athenian Empire---Classical Athens.  The mines were abandoned in the 6^th Century A.D and reopened in the 1880s producing lead, silver, cadmium, manganese and helped finance the building of the modern country of Greece.  The ore deposits became exhausted in the 1980s. (above information from www.ancient-greece.org).

Photomicrograph of rosettes of lath-like crystals of serpierite collected from the Creole Mine, Beaver County, Utah. Width FOV ~1 cm.

My second specimen of serpierite was taken from the Creole Mine in Beaver, County, Utah, one of the more mineral-rich counties in western Utah.  Information about the mine is tough to locate; however, it was mined for scheelite crystals prior to 1943. Hobbs (1944) reported that several hundred tons of ore containing 0.75% WO₃ were mined out by 1943.  Prior to that mining activity lead and silver ores (probably silver- rich galena) were taken from “massive sulfide replacements in limestones along the contact of a quartz monzonite or granite dike.”  The scheelite was located in the overlying oxidized zone in masses of “limonite.”

Photomicrograph of numerous platy lathes of serpierite? Collected from the Bay Horse Mine, Challis, Custer County, Idaho. Width FOV ~7 mm.

Back in the 1980s I had an opportunity to help write an Environmental Impact Statement for a proposed fluorspar (fluorite) mine near the old ghost town of Bay Horse in the mining region of the same name.  Specifically, I was looking at the paleontological resources, if any, in the area of the proposed mine.  I do not remember all of the details except that we camped south of Challis along the beautiful Salmon River, the local population was not overly friendly to strangers, and the massive deposits of the Tertiary (Eocene, ~50-55 Ma) Challis volcanics held a gazillion pieces of petrified wood.

The rocks examined at the proposed mine were part of a thick section of something like 35,000 feet of Paleozoic marine rocks that have an extremely complex stratigraphic and structural history (Hobbs and others, 1991).  About the only fossils I remember finding (but again my memory sometimes fades) were numerous graptolites in the black shales.  It was sort of eerie driving through a deserted “ghost town” in remarkably good shape. The area was privately owned and we did not stop to explore.

Part of the Bay Horse Mining District now incorporated into the Land of Yankee Fork State Park.  Photo courtesy of www.deq.idaho.gov.

The Bay Horse mining area deposits were first noted in 1864 by a prospector traveling along the river but the first lode claim was not located until 1873.  In 1877, a major lead-silver vein was discovered and by 1878 a gold/silver rush to the area had begun. The metals were found in replacement ore bodies (probably associated with Cretaceous and Tertiary intrusives).  In 1880, a 30-ton smelter was constructed, and within two years charcoal kilns were constructed to provide the smelter with a local fuel source. By this time, the town of Bay Horse had a population of about 300 and a complex of substantial, permanent buildings.  Only nine years later in 1889 the smelter closed.  Evidently smaller scale production continued until 1925 as the ore was transported south to a smelter in Clayton.  The Bay Horse District was a quite productive area as total mineral production is estimated at ~200 oz. of gold, 6.3 million oz. of silver, 6.6 million lbs. of lead, and 39 thousand lbs. of zinc. (above from www.deq.idaho.gov)

   

Since I visited the area the State of Idaho made a great decision and purchased the Bay Horse area and renamed it the Land of Yankee Fork State Park.  I look forward to returning. And, I never paid much attention to note if the fluorspar mine was ever completed.

  

My third specimen of serpierite has an older looking label stating it was collected in the Bay Horse area at Challis, Idaho.  However, the descriptions of serpierite at www.mindat.org do not recognize the mineral at Bay Horse.  But I did find a reference in the Handbook of Mineralogy, www.handbookofmineralogy.com  noting the occurrence of serpierite from the Bay Horse Mine at Challis.  Maybe?  Maybe not?

REFERENCES CITED

Hobbs, S.W., W.H. Hays, and D.H. Mcintyre, 1991, Geologic map of the Bayhorse Area, Central Custer County, Idaho: USGS Miscellaneous Investigations Series Map I-1882 pamphlet.

Hobbs, S.W., 1944, Tungsten deposits in Beaver County, Utah: USGS Strategic Minerals Investigations Bulletin 945-D. 

AND SPEAKING OF ARIZONA GOLD AND ORANGE! 

BLUE LAVENDULAN: TUCSON 2016

The Kino Gem and Mineral Show is one of the larger venues housing items for sale at the Tucson shows.  In 2016 there were 205 vendors listed; however, it seems increasing difficult to purchase individual mineral or rock specimens.  Instead there are a wide variety of somewhat bizarre items for sale including guns (this is Arizona), “coon skin” hats complete with tails, authentic animal fur and skins, incense, gongs and brass items direct from Asia    The tents are set up at the Kino Sports Complex in south Tucson and are a mixture of individual tents and the large football field size units.  One large unit houses dealers displaying a great variety of lapidary machines while another tent has smaller kiosks stocked with overpriced jewelry.  What is missing are the small mom and pop operations that were once the heart of the venue---essentially booted out.  But life goes on as buyers could locate a great variety of amethyst cathedrals and smaller broken pieces. 

I do like the colors in this large concretion with internal agate banding.

And away we go to explore the offerings.

I always enjoy seeing specimens collected from siliceous hot water deposits near Milford, Utah.

Anything you need from southeast Asia, except rocks and minerals.

Here is my favorite guy at the venue offering tasty snacks.

So this is Arizona and maybe rockhounds need to shoot claim jumpers.  Of course it is not uncommon to see, as Marty Robbins sang, "the big iron on his (her) hip."

Every rockhound needs genuine hide or fur to line their cases and drawers.

I always thought these were natural lingam stones but now realize they are linga (plural). I also believed they were collected by natives from a sacred river in India.  Somehow doubts creep in when I see thousands and thousands for sale in the US being pawned off as Hindu religious items guaranteed to increase your masculinity.

At last a shop selling rocks and minerals!

What appears as a crust of blue lavendulan (copper arsenate) is actually hundreds of tiny thin platy crystals; however, they measure in individuals less than 1 mm and are beyond the range of my scope.  The R points to one of a cluster of radiating individual crystals.  Total width FOV ~ 7 mm.

And, looking really hard at some stock I was able to locate a really nice piece of blue lavendulan.  The specimen appears as sort of a crust of intense electric blue on the matrix.  However, on closer examination under high power one can observe the crust is actually composed of very tiny aggregates of thin platy crystals, some of which form rosettes. An older label indicates collection at El Guanaco Mine, Santa Catalina, Antofagasta Province, Chile where MinDat noted 31 valid minerals and two type localities.  At the mine copper and gold veins are emplaced in Upper Cretaceous and Paleocene volcanic sequences.  I presume, but am uncertain, that both the copper and the arsenic could be the result of oxidation of the primary mineral, enargite [Cu₃AsS₄].

Lavendulan [NaCaCu₅(AsO₄)4Cl-5H₂O] is a hydrated copper arsenate and forms as a secondary mineral in “oxidized zones of some copper deposits” (MinDat).  So far, so good; however, I need to rely on the label for identification since a very similar mineral, lemanskiite, is known from the location (discovered in 1998).  In fact, the mine is the type locality for this copper arsenate.  Lemanskiite and lavendulan have exactly the same chemical formula but belong to different crystal systems-they are polymorphs.  Lavendulan is Monoclinic and lemanskiite is Tetragonal.  Trying to visually identify lavendulan from lemanskiite is above my pay grade!

As noted in other postings the arsenate radical (AsO4) is similar in size to the phosphate radical (PO4) and they often interchange.  Well, sampleite is a copper phosphate in a solid solution series with lavendulan.  If one substitutes lead for the calcite in lavendulan the mineral becomes zdenekite.  Learning is “fun”! 

So I am calling these tiny crystals lavendulan since I don’t carry around an XRD or something but knowing I well could be wrong!  These great- colored crystals have a vitreous to maybe a sub vitreous luster, are brittle, translucent, commonly cleave or fracture, and are quite soft (~2.5 Mohs).  Looking closely one can observe twins and the streak is a light blue.

I love life.  There’s so much to learn and see all of the time, and nothing nicer for me than to wake up, and the sky is blue.   Pattie Boyd

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.