BLUE COPPER SILICATES; KINOITE & STRINGHAMITE

A subtitle for this Blog might be "I wish to become a better mineralogist :) and to acquire a finer binocular scope with a nice powerful camera."

I always considered geologists, especially soft rockers and paleontologists, as historians---we just studied “older” items and events.  Perhaps that is why I continue to study “history” and relate events in “modern’ (post 1943) history to events in my life.  The year 1967 sticks out in my mind for several reasons, not the least of which was the completion of an MS Degree (Geology) from the University of South Dakota (USD).  The number of U.S. troops in Southeast Asia increased to about half a million and even here in the Heartland there were negative rumblings about the prolonged conflict.  USD had an ROTC program and the recruiting (among students) for commissioned officers seemed to be more intense in 1967 than in 1965 when I first arrived in Vermillion.  I enjoyed my two years at USD and made many friends and acquaintances, mostly students from small communities in South Dakota, Minnesota and Iowa holding similar values as mine.  In fact, I decided to attend USD due to its small size---similar to my undergraduate institution in Kansas.  I was just a small-town kid who liked to collect rocks!

Vermillion, like most college towns, had a plethora of watering holes with undergraduates frequenting such places as the Rathskeller and the Varsity.   Carey’s was a “locals” hangout and the owner really did not appreciate a college crowd.  The graduate students (older in age and wiser) enjoyed the Charcoal Lounge (CharBar), a “21 bar.”  For special events we visited the Black Steer in Yankton (rarely, as it was expensive, or so it seemed to poor students).

Good geology was a little scarce around Vermillion—a few outcrops of Cretaceous rocks sticking up through the glacial crude or exposed along the Missouri River.  But, there was always an excuse to visit the Black Hills in “West River” thinking nothing of driving 400+ miles, one-way, in a long weekend!  It actually was closer to visit my home in Kansas, 325 miles, than take a trip to the Hills.  But hey, there were lots of interesting rocks out west.  I fell in love with the Hills and still enjoy, immensely, my continued trips.

For my thesis I picked an area out in the badlands south and west of the National Monument and examined some late Tertiary gravels. I really did not do a very good and scientific job but certainly had a great time collecting and camping and looking at rocks.

The other important event of 1967 (late summer) was embarking on a long-term commitment (47 years and counting) with my spouse.  I had made up my mind in an earlier year that current schooling was only hitting the fringe of geology and that a more advanced graduate degree was in my future—I hoped!  So, I begin to submit applications and was somewhat hesitant since I certainly was not the University’s brightest student; however, I loved classes and was persistent in applications.  Turns out I received several offers from some major institutions; however, I wanted to “go west.”  I was ecstatic when the University of Utah called with an appointment and I immediately accepted.  My adviser was not pleased since there were other accepting institutions with “major” reputations; however, I wanted “mountains,” not reputations!  So, in about a 10 day period, I graduated from USD, got married, informed my draft board, and headed to Utah.  It was an exciting, and frightening, time. We headed to Salt Lake City in a 1959 Pontiac, ~$250, and listening to the Rolling Stones, the Doors, and the Beach Boys (we were not fans of the later Beatles nor Isaac Hayes).  But with an AM radio one did not get much of a choice in western Colorado and eastern Utah! (See Blog August 21, 2012: Utah Petrified Wood and Flower Children).

A commitment that has reached 47+ years and counting. 

We located an apartment near campus where I could walk to classes, a “cheap” apartment where the landlord agreed to split our rent of ~$70 per month into two $35 payments.  I was excited about classes and promptly marched over on Monday morning to my 7:00 class, a non-credit “hazing” offering called Ph.D. French (or something close).  In those days, in a cherished (by the faculty?) rite of passage, science students needed to have reading proficiency in two foreign languages.  The classroom, and really the building, was rather empty at 7:00 am but I promptly took my seat at 6:45 and waited, and waited, and waited, becoming more frightened with each moment.  Finally it was nearing 8:00 am and I left and headed over the Registrar’s office with my schedule.  The person behind the desk took a look, and promptly thought “what sort of a dofus are we admitting these days?”  Sir, she announced, this class is at 7:00 pm!  OK!  At my previous institutions night classes were essentially non-existent.  Let the kid out of the sticks and look what happens.  

  

As noted in other Blogs, the University of Utah, was following an “old school” model and had Departments of Geology, Mineralogy and Geophysics.  I had settled in with Geology and rarely had contact with the other two areas—except on one occasion.  I was exploring dissertation projects and my adviser sent me over to visit with the Chair of Mineralogy—Dr. Bronson Stringham.  Dr. Stringham had spent his early years working in southern Utah with the famous Dr. Herbert Gregory and my adviser though perhaps he could offer suggestions for a project.  I actually was quite frightened since Dr. Stringham had the reputation, at least among the geology students, of chewing up and spitting out non-mineralogy students.  It turns out that he was a really nice guy, very interested in field geology, and quite informative.  Unfortunately, Professor Stringham died that same year.

All of this banter leads to a copper mineral named after the Professor, stringhamite.  I had never heard of this mineral until I ran on to callaghanite, a copper magnesium calcium carbonate, named after Dr. Eugene Callaghan, the Chair of the newly minted (1968) Department of Geology and Geophysics at the University.  See Blog Callaghanite: a Rare Blue Carbonate (May 5, 2014).

The above two photomicrographs are isolated crystals (non-striated) of stringhamite.  Each is less than 1 mm in size. Collected from Christmas Mine.

Dark blue crystals of stringhamite (S) with lighter blue kinoite (K), tiny fibers of torbermorite (T) [Ca₄Si₆O₁₇-2H₂O]-(Ca-H₂O), clear “cubes” of apophyllite (A), and white xonotlite (X) Ca₆(Si₆O₁₇)-(OH)₂. Collected from Christmas Mine.  Width FOV ~5 mm.

Stringhamite, a hydrous calcium copper silicate [CaCu(SiO₄)-H₂O], is a rare mineral being only found (according to MinDat) at single localities in Japan and Chile, and in Arizona (Christmas Mine and Twin Buttes Mine), California (Crestmore Quarries) and Utah (Bawana Mine, the type locality).  Stringhamite crystals are a beautiful dark blue to blue-violet to azure blue in color.  They have a nice vitreous luster and are transparent to translucent. Most crystals are very tiny, on the order of less than one mm. 

I find it extremely difficult to identify the differences between stringhamite and kinoite, also a hydrous calcium copper silicate [Ca₂Cu₂(H₂0)₂(Si₃O₁₀], when the two minerals are found together.  Kinoite is also a vitreous deep blue color and generally transparent.  At the Christmas Mine south of Globe, Arizona, the source of most kinoite on the current specimen market, the crystals often occur as sprays and are striated.  This latter point is about the only way that I can differentiate the two minerals---assuming I can do such!  In addition, stringhamite seems to occur as isolated crystals as opposed to kinoite sprays (my opinion).  Kinoite crystals seem larger than stringhamite but are still mighty tiny.  At the Christmas Mine kinoite is also intimately associated, in many specimens, with crystals of fluorapophyllite-(K) [KCa₄(Si₈O₂₀)F,OH-8H₂O].  In fact, most market specimens are numerous blue kinoite crystals perched on colorless fluorapophyllite (or maybe hydroxyapophyllite, I cannot tell the difference since there is a solid solution series).

A spray of kinoite about 1.3 mm.

I find it interesting that in the few western localities (Christmas Mine, Bawana Mine, Santa Rita Mountains, AZ), kinoite and stringhamite are contact metamorphic minerals (skarn) situated between limestone and igneous intrusions. However, kinoite is also found in the copper country of the Keweenaw Peninsula of Michigan.  Here the mineral is associated with the basalt extruded during the rifting of the North American continent during the late Precambrian (see Blog Denver Gem Show: Copper 2012; April 7, 2013)

The Christmas Mine has produced some fascinating mineral specimens and I wish that my mineralogical skills (and microscope) were more advanced!  I have four small samples from the mine and they have a variety of minerals present.  Unfortunately, the crystals are quite small and difficult for me to identify.  The mineralization seems to be in a contact metamorphic zone between upper Paleozoic limestones and a quartz diorite intrusion although there is some mineralization between the limestones and the overlying Cretaceous volcanics.  The mine is a former surface and underground Cu-Au-Ag-Mo-Bi-Pb-Zn-Be-W mine operating from ~1900 until it closed in 1982.  Copper seemed to have been the main commodity although gold and silver were byproducts (above information from www.MinDat.org).

Thus far I have been able to identify (I think) apophyllite, kinoite, stringhamite, gilalite, grossular, black tenorite (probably), calcite, ruizite (questionable), native silver (questionable), cuprite (maybe) and unknowns (definitely).

The best known specimens of kinoite are the blue crystals on apophyllite.  Width ~1.9 cm.

A photomicrograph with some unknown minerals. The T? pointing to the masses of a non-crystalline black mineral could be the copper oxide tenorite [CuO].  The A? seems like apachite [Cu₉Si₁₀O₂₉-11H₂O], a rare copper silicate first described from the Christmas Mine.  The R? is a sphere of orange ruizite [Ca₂Mn₂{(OH)₂lH₂Si₄O₁₃}-H₂O]—maybe!  In very high magnification this dark blob on the photomicrograph appears as a bundle of dark orange crystals.  Again the type locality is the Christmas Mine.  The green spheres are gilalite, shown below.

Besides the kinoite and stringhamite, the most interesting is gilalite, a rare copper silicate [Cu₅Si₆O₁₇-7(H₂O)]. Like the other Christmas Mine minerals, gilalite is a sulfide skarn deposit (near junction of limestone and an igneous intrusion).  The type locality for the mineral is at the Christmas Mine where the specimens are green spherules.  When broken the spherules are bundles of radiating fibers. According to MinDat, gilalite is only found at the Christmas Mine, and single localities in Nevada, Greece and Brazil.  In my Christmas Mine specimens these green spherules are numerous.

The individual spherules of radiating fibers are less than .5 mm each. In the center of the photo are some nice gemmy and clear cubes (although some are partially included) that look like fluorite (but that mineral is not listed as present at the Christmas mine).  A very minute crystal of stringhamite is in the upper right quadrant.  I believe the yellow-orange clusters are grossular garnet.

The second location of kinoite in my collection is from the copper country of Michigan, the Keweenaw Peninsula of the UP (home of the Yoopers---see below).  The Laurium Mine is near the old company town of Laurium (named for the famous mining town in Greece).  The mine later became part of the Calumet & Hecla Mine.  According to MinDat, the prospect was discovered in 1904 and a shaft was sunk in 1907.  Mining reached about 1000 feet but the mine was closed in 1920 due to flooding.  My quite small specimen has kinoite, epidote, calcite, quartz, and a very red copper mineral (maybe cuprite Cu₂O).

Crystals of green epidote (left).  FOV width ~6 mm.

Cu₂O

Crystals of kinoite as well as kinoite included in calcite.  The red mineral is a copper mineral and may be cuprite.  FOV width ~6 mm.

One of the great mineral museums in the country is located at Michigan Tech University (Houghton)---the A.E. Seaman Mineral Museum.  If you are ever in the UP make certain to visit the displays (www.museum.mtu.edu).

One of the everlasting questions in the snow/mosquito belt (Minnesota, Wisconsin, and Michigan) is:  What Da Heck Is A Yooper? The people that live in the Upper Peninsula or the U.P. are called "Yoopers" and are proud of it. The people that live under the bridge [Lower Michigan] are called "trolls." The song "I'm a Troll Man" was written about them. Lots of trolls from down below dream about moving to da U.P., but there's no work here. So we let them come up to relax, enjoy and spend their cash, but they gotta go home afterwards (www.dayoopers.com)

So, in the spirit of the holidays, I present Da Yoopers (a group—see site above) most famous song (sung to the tune Jingle Bells):

C'mon, cmon!
C'mon, you can do it!
(car starts)
All right!
Dashing through the snow
in my Rusty Chevrolet
Down the road I go
Sliding all the way
I need new piston rings
I need some new snow tires
My car is held together
By a piece of chicken wire
CHORUS
Oh, rust and smoke, the heater's broke
The door just blew away
I light a match to see the dash
And then I start to pray
The frame is bent, the muffler went
The radio, it's okay
Oh what fun it is to drive
This Rusty Chevrolet
I went to the IGA
To get some Christmas cheer
I just passed up my left front tire
And it's getting hard to steer
Speeding down the highway
Right past the Neguanee cops
I have to drag my swampers
Just to get the car to stop
(chorus)
(instrumental)
Bouncing through the snowdrifts
In a big blue cloud of smoke
People laugh as I drive by
And I wonder what's the joke
Got to get to Shop-Ko
To pick up the lay-away
'Cause Santa Claus is coming soon
In his big old rusty sleigh
(chorus)

Check it out at: www.youtube.com/watch?v=50IgzksUqpQ