A BREAK FROM THE MINERALS: SCIENCE WILL WIN

In this time of in-home sheltering, and thinking that my age puts me in the at-risk group, I certainly have given thought to “my life.”  Part of this remembering is probably a normal process when one ages and starts to think about their mortality; however, the coronavirus pandemic sort of exacerbates the situation and moves it on the front burner.  So far, I have made it OK, and hope for a well future.

I essentially have stopped watching most TV news and conferences except to check the local weather.  I want the country to leave disease control to the medical personnel and research scientists.  My only hope for our country, and the world, is THAT SCIENCE WILL WIN IF WE GIVE IT A CHANCE.


I also have reshaped my time to restack and “clean” my office, refile the books and magazines, and sort the minerals.  That has been a pleasant sort of exercise and has brought back many fond memories but:

You can't reminisce too much. Because you've got to keep pushing forward, you know?                  Daniel Caesar


My pushing forward is trying to understand the mineral chemistry of boron, and the boron minerals.  I am having troubles with the chemistry (even after help from Yooper Pete in Denver), so sometimes I must take a break and revert to reminiscing about youth, especially the geology aspect of “growing up.” I often wonder  how my younger years affected my career choice and then think that my entire life choices are probably due to: 1) growing in in a rural area with nurturing parents who let me explore the “outdoors” and tune into nature; 2) caring and enthusiastic primary and high school teachers (47 students in high school) where four years of English, four years of math, four years of science, and four years of history/civics and social science, prepared me for college (and life); and 3) geology instructors who mentored me all those years, even during the times I was greatly confused with crystallography and stereonets (still am).

The VO₄ vanadium anion that is an integral part of the vanadate minerals.

I was rummaging around my office and came across a few geology items that brought back the memories.  A couple of years ago one of my former institutions found (in a dusty storage closet) and returned my Optical Mineralogy notebook.  That sucker had not seen the light of day in 50 years.  Although I turned out to be a softrocker and paleontologist, I thoroughly enjoyed Optical Mineralogy and Optical Petrology while attending the University of South Dakota.  It seems as if I spent hundreds of hours looking down that B & L single tube scope.  For a while I thought my right eye (dominant) was larger!  That also was when I finally determined (with a physician) that I really was color blind with several colors (red-green-brown; blue-purple).  The instructor would talk about thin section mineral colors and pleochroism and I was totally lost with some slides.  This deficiency later bit me in the derriere when I tried to enlist in the commissioned corps of U.S. Coast and Geodetic Survey (since engulfed by other federal agencies) and was informed that men with color blindness could not serve on their ships; a disappointment for me.  The recruiter suggested that I try the U.S. Army since color blind men often have a great perception of different shades of gray and therefore are quite good at working with air photographs (pre color).  The Army was in need of people who could examine air photos and pick out “things” hidden in a jungle environment.  I passed on the opportunity. 

An Introduction to the Methods of Optical Crystallography, by F. Donald Bloss, was first published in 1961. That edition still stands as a classic in the field...and for many years it remained a widely used textbook for undergraduate courses in optical mineralogy. Review in American Mineralogist 2002.

At any rate, each optical student had to keep a notebook describing the thin sections we observed and information we could use to identify different minerals.  Now, my artistic abilities floundered here but I struggled along using drafting and colored pencils to sketch minerals.  I thought of this notebook when I learned on the Rockhounds List that Donald Bloss, the author of my text An Introduction to the Methods of Optical Crystallography recently passed away at the ripe age of ~100.  I am certain that geologists of my age, and later, cut their optical mineralogy teeth with this book.

Speaking of older gentlemen, Bob Dole (now closing in on 100), was a member of the U.S. House of Representatives when I was growing up in Kansas.  He knew my parents from their mutual interest in the American Legion, an organization that World Wat II vets joined by the tens of thousands after the conflict ended.  My parents were “proud as pie” when Rep. Dole wrote them a letter about their son!

When I reveal to young persons some of my mineral/fossil collection, I always pull out an item and tell them “this is the reason I did not become an engineer.”  I show them a slide ruler and tell them it is a mechanical analog computer, yes a computer.  In college I just did not have the brain power to function well with this computer.  In some math and physics courses I had no choice since trig functions, logarithms, square roots etc. were essential to “passing the test.”  I just was not very skilled and certainly was not a geek who carried his (not many hers) ruler in a case clipped to his belt and called it a slipstick.  Most students of my age remember the science classrooms where a six- or seven-foot slide ruler hung on the wall above the blackboard and was used by the instructor for teaching.

The middle section of the slide ruler slide back and forth, left and right, while the clear cursor moves along the entire ruler, usually about 10-12 inches.

As a geology student, my classmates and I spent a fair amount of time outside working with maps and rocks.  Two of the staples of an undergraduate curriculum were courses in field methods and field camp, and the Field Methods text by Robert Compton. Field methods often involved constructing a topographic map using an alidade and stadia rod (the stick).  This was time consuming process as the alidade and board had to be completely level in order for accurate readings.  In larger scale projects, especially in field camp and project field work, we depended on hand levels, or sometimes on Jacob Staffs (Jake Sticks), and always on the staple Brunton Compass.  Today, with laser beams, satellites and GPS, and even cell phones I don’t know if students even know how to use a Brunton or hand level.  But that is OK as time moves on.

A hand level with its leather carrying case.  My eye height was 6 feet.  By looking through the telescopic tube, and keeping the bubble (on top of the tube) level, I could mark a spot on an outcrop or hill that was six feet high.  Walk up to that marked spot and shoot a new sight, etc.  After a while I could determine the height of the hill:  six shots times six feet equals 36 feet in elevation for the hill.  This level was even more sophisticated in that it could read stadia rods for more precise readings.

Plane table and alidade.  The surveyor/geologist is looking toward his partner holding a measuring stick (stadia rod).  Photo from sale items on EBAY.

The pocket Brunton transit for taking directions and reading slopes and angles. It took some skill and a steady  hand to use a Brunton accurately.  The Brunton could also be used as a hand level.

All geology students made their own Jake Stick, usually out of a thick dowel rod.  It was cut exactly to your eye height and a bubble was attached so it replaced a hand level.  In addition we stuck a rotating protractor on the stick in order to read the thickness of dipping beds.  A simple but nifty non-electronic instrument

Four other “must have” tools were: 1) an Estwind rock hammer; 2) a ten-power hand lens for magnification; 3) a pocket stereoscope for examining air photographs; and 4) a quality field notebook with appropriate pencils or permanent ink pens (no ball points). Nice to have tools were a hardness kit, either home-made or purchased, a tape measure, and a color chart.  I still have all of my original equipment except for the Jake Stick, the color chart and tape measure.  Of course, there were also the traditional army surplus canteens, knives, shovels, packs, coats, etc, and purchased cloth collection sacks (sample bags from drilling rigs).  Geology students, and other outdoor enthusiasts, were always on the lookout for surplus stores.  My favorite was in Fort Collins, Colorado.

The center hand lens was my original from the 1960s, the one on the right has both LED and UV lights, the left one is also lighted can easily lay on your desk or be carried in a jacket.

On geologic mapping projects we often used air photos obtained from federal agencies.  In order to see three dimension landforms on the photos a pocket stereoscope was used in the field while a larger mirror scope was available in the lab

What is left of my hardness kit with points of different hardness minerals mounted.  I also used a steel pocket knife and a quartz crystals and an unglazed piece of porcelain served as a streak plate.  A small bottle of acid (HCL usually) finished off the tools. 

Estwing pick and chisel head hammers (from their website).

My first rock hammer in Kansas had a chisel point with a leather handle.  The chisel was good for breaking shale.  Before heading to Field Camp (see Posting June 19, 2015) I purchased a blue handle, pointed pick for the hard rocks I would find in Colorado.  I have gone through several loupes but still have the original, along with a new one that is lighted with LED and UV.  My notebook with all of my dissertation field notes is filed with other books; however, earlier notebooks were misplaced (another word for lost).  I am not certain that air photos are still in use with computer programs such as Google Earth, widely available (and free).
  

One of the reasons that I became a paleontologist is due to the first, really nice fossil I picked up in a gravel pit.  The lower jaw of Bison sps., probably Bison bison, came from a deposit of Pleistocene gravel (a pit) along the Solomon River in Ottawa County, Kansas (my home county).  Now I had collected other miscellaneous items such as Cretaceous leaves (Dakota Formation outside of town) and Cretaceous clams and shark teeth (Greenhorn Formation on the numerous rock fenceposts) but this jaw was really, really nifty to me.  Wow.  What a find.  There was even a small article in the county newspaper about the discovery (somewhere in my files) by the”local kid”.  I believe this was a critical point in my life, a star guiding me to a career.

And finally, a textbook from my graduate days at the University of Utah.  Probably the finest instructor that I had in my higher educational experience was Armand J. Eardley.  Dr. Eardley was a geologist/gentleman in the old-time sense with khaki pants, often a tie in the field, and a gentle demeanor that led to a fantastic relationship between Dr. Eardley and his students.  He also was a tremendous help when it came time for my dissertation.  But perhaps the best advice I received from him was something like the following:  As a geologist and University instructor I spent much time attending meetings and working in the field. Always mentor your students and take them along to meetings. And,  I never forgot Mrs. Eardley at home, and she was particularly fond of silver jewelry.  Remember that as you move on in a career—I did.

Mentoring students Uinta Mountains, Utah.

“The past is a candle at great distance: too close to let you quit, too far to comfort you.”    Amy Bloom

AN OUNCE OF OSUMILITE (NIFTY MINERAL)

If you believe in science, like I do, you believe that there are certain laws that are always obeyed.             Stephan Hawking

We live in a society exquisitely dependent on science and technology, in which hardly anyone knows anything about science and technology.                      Carl Sagan

If the facts don't fit the theory, change the facts.   Unknown

We have come to Day ? of our self-quarantine and what day of the month is it?  Just like the movie Groundhog!  The quotes above just seem to fit my current mindset.  But, I am an optimist at heart and look at the good things in our lives—like sunsets!

The Cascade Volcanoes are the best-known volcanic mountains in the lower 48 states.  The high peaks dominate the Cascade Mountains that extend from British Columbia, Canada, south to California.  The general public is fascinated by the 14,000+ foot Mt. Rainier with its glaciated topography to Mt. Saint Helens that blew its stack in 1980 to Crater Lake with its pristine lake inside the caldera. In southern Oregon is an area well known to hikers and Native Americans as the Three Sisters, each volcanic peak is in excess of 10,000 feet in elevation.  South Sister erupted about 2000 years ago while Middle and North Sisters are fairly dormant (so they say).  Most of the area around the Sisters is protected as a Wilderness (official designation) including a piece called Obsidian Cliffs.  Obsidian is natural glass that forms when rhyolitic magma, the volcanic extrusive of granite, cools very quickly and cannot form crystals.


The volcanic Cascades are the result of a remnant of the Pacific Farallon Plate, the Juan de Fuca Plate, subducting under the North American Plate.  The Farallon Plate, an oceanic plate, was formed along a Pacific Ocean ridge (modern terminology) similar to the current Mid Atlantic Ridge and was transported east (current direction) pushing several “microcontinents”  into the North American Plate and “sticking” them to the Plate. In time, the heavier Farallon Plate was almost completely subducted under the lower density North American Plate leaving behind a few remnants such as the Juan de Fuca.  Another possibility is that the North American Plate overrode several different Pacific trenches (rather than a single Farallon Plate) while incorporating microcontinents into our North American rock column. At any rate, both theories allow for massive mountain building and associated volcanism as either the Farallon Plate or the oceanic trenches were subducted.  The North American Plate movement and oceanic plate subduction created heat and pressure while melting the subducted rocks and releasing energy on the surface in the form of massive volcanism, and mountain building.  Literally the entire western United States has large-scale exposures of extrusive and intrusive volcanic rocks such as basalt, quartz latite and rhyolite (and its relatives welded tuff and ash falls).

Diagrams of Juan de Fuca Plate. Public Domaine but Courtesy of Alattaristarion.

The mountain building and volcanism started in the Jurassic and continues today as noted by the explosion of Mt. Saint Helens in1980.  The Cascade volcanoes are the result of the Juan de Fuca Plate being subducted with resulting deep melting and surface volcanism.

As a soft rocker and paleontologist I never paid much attention to the explosive and extrusive rhyolite, welded tuff, and other siliceous volcanics that are usually a mixture of quartz, sanidine, and plagioclase, until I discovered topaz crystals out in the Thomas Range of western Utah (see Posting     ), and red garnets in the Ruby Range of Nevada, and at Ruby Mountain, Colorado (see Posting May 20, 2014).  There were also some much smaller crystals in the rocks such a biotite, hornblende, and pseudobrookite (see Posting  ) that did not attract much of my attention.  Little did I know that a nifty mineral called osumilite was also lurking in the rhyolite of Obsidian Cliffs, Oregon, and a few other localities. 

Submillimeter (~.75 mm) crystals of osumilite from Obsidian Cliffs, Oregon.

Osumilite grabbed my attention since the mineral is a very rare potassium-sodium-iron-magnesium-aluminum silicate that has very tiny, nicely formed, tabular, hexagonal crystals.  They usually have a blue color that is dark enough to appear black, a shiny adamantine luster, are transparent to translucent, and are somewhat hard at 5-6 (Mohs). The mineral just sort of “grabs you” when looking at nondescript rhyolite under a scope and up pops this nifty crystal tab.  Besides rhyolite, osumilite sometimes appears in volcanic dacite, and in high grade (ultra-high temperature) metamorphic rocks.  Once observed, you will not confuse osumilite [(K,Na)Fe,Mg)₂(Al,Fe)₃₍Si,Al)₁₂O₃₀] with other minerals.  Electronic gizmos can determine which cation is dominant, iron or magnesium, so a mineralogist can add –(Mg) or-(Fe) on the end of the formula!


As we continue to shelter in place I continually think about the future and what it will bring.  And why, why, why?  Is anyone to blame?  But mostly I think about my good life and all that it has brought, and I am well and safe.


Everything happens for a reason' is something that we have to tell ourselves all the time, because it's good to have the idea that something good is around the corner.

        Margot Robbie

A CUP OF CUPRITE

A rockhound getting to know you over a cup of lager: Are you full of  beryllium, gold, and titanium, because you are Be-Au-Ti Full.

Well, one day moves on to another when one is sequestered in your home.  But, as previously stated I am well and safe and often think about those who have lost shelter, food, and a job.  I also thank those medical workers who dedicate their careers, and lives, to protecting others.  For now, I just continue to move from one day to the next with much reading and writing.

Winter arrived again in Colorado Springs with 8 inches of snow and a record low temp of 7 degrees.  Of course, that seems warm to Leadville’s -7 degrees.  Oh well, the sun and warmth will return. 

I have been rummaging around in my minerals and came across some copper oxides and decided to explore their origin in a bit more detail.  So, here goes. 

Minerals, the chocolate chips in the cookies of life.

The oxide minerals are highly desired by many rockhounds as many are colorful with visible crystals.  They usually form in the oxide zone of metallic ore deposits as a result of chemical decomposition of the primary sulfide ore minerals.  This decomposition is the result of groundwater, surface water, oxygen and carbon dioxide causing a chemical change in the unstable sulfides.  Some of the products are the oxide minerals where the oxygen anion with a 2- oxidation state combines with metal cations (positive oxidation state).  One oxide that often has nice colors and beautiful crystals are the copper oxides.


Copper can combine with oxygen in a couple of different ways : copper (I) oxide and copper (II) oxide but also known as cuprous oxide and cupric oxide.  Oxygen, the negative anion, bonds with metal cations by accepting two of their electrons. In cuprous oxide (copper I) two different atoms of copper each donate one electron and the chemical formula is Cu₂O, also known as the mineral cuprite.  In cupric oxide only one atom of copper donates two electrons and the formula is CuO, known as the mineral tenorite. The bonding in copper oxide is ionic--an electrostatic attraction between the positive and negative ions.

Public Domain.  Artist unknown.

Copper is Element 29 on the Periodic Chart of the Elements with copper containing 29 electrons (negative) in outer shells and 29 protons (positive) in the nucleus.  The “normal” electron configuration is 2, 8, 18, 1 as shown above.  Notice that there is a single electron in the outer shell.  When oxygen combines with that single lonely electron the result is Cu₂O or cuprous oxide or cuprite—copper with a 1+ oxidation state combining with one atom of oxygen with a 2- oxidation state so you need two coppers, each with a 1+ oxidation state.  In cupric oxide, tenorite, the oxygen not only takes the lonely outer shell electron to the dance but borrows a second electron from the next orbit and the formula becomes CuO.  Cuprous oxide then has a monovalent cation (the copper) but in cupric oxide where the oxygen borrows 2 electrons the cation copper is a divalent cation.  The cuprous oxide is very stable since there are no open slots on that full penultimate orbit ring (filled and half-filled shells are the most stable). 


Cuprite is one of the best-known copper minerals due to its often-dark red color and octahedral, cubic, or dodecahedral crystals (Isometric Crystal System); however, the red is often so dark that crystals appear black. Cuprite is soft at 3.5-4.0 (Mohs), is very brittle with a conchoidal fracture and a luster that ranges from adamantine to earthy.  It has a brownish-red streak and is transparent to translucent in thin sections. On prolonged exposure cuprite crystals lose their luster and become gray to gray black in color.

Diagram octahedron crystal.

Above three photomicrographs showing dark red octahedrons of cuprite, each crystal less than 1 mm in width.

Extremely small, but very colorful, cuprite crystals on native copper..  Width FOV top: ~8 mm. Width FOV middle: ~4 mm. Width FOV bottom: ~6 mm.

Cuprite is a secondary mineral resulting from the oxidation of primary copper sulfide minerals such as bornite and chalcopyrite.  My specimen is from the Ray Mine northeast of Tucson in Pinal County, Arizona.  Mineralization at the Mine is a porphyry copper deposit (see Posting March 2, 2015).

Needle like crystals of cuprite v. chalcotrichite. Width FOV both ~1.0 cm.  I presume the matrix is goethite/limonite.

I have two other specimens from the Ray Mine are a variety of cuprite called chalcotrichite.  Here the crystals ate not octahedral but greatly elongated capillary or needle like forms.  I really don’t understand about the formation, or the why, of these elongated crystals and had difficulty in locating a good reference.  For those of you interested check out the 1983, vol. 68 of the American Mineralogist, page 790 ff: A TEM study of fibrous cuprite (chalcotrichite); microstructure and growth mechanisms.  Trying to abstract that article for the Post is above my pay grade.  Online at: http://www.minsocam.org/msa/collectors_corner/arc/cuprite.htm.

Photomicrograph of banded chalcedony and tenorite.  Note botryoidal calcite in upper left quadrant.  Width of photo ~1.2 cm.

Blue chalcedony and black tenorite.  Width of photomicrograph ~1.2 cm.

Photomicrograph banded chalcedony left grading into blue chalcedony or silica infused chrysocolla surrounding black tenorite.  Notice green ?chalcedony encased in the blue.  Width of photo ~1.2 cm.

Cupric oxide is recognized in the mineral world as tenorite, a black copper oxide (CuO).  Tenorite would not be an impressive mineral with its earthy to dull to metallic luster and generally massive habit without common accompanying friends—colorful chrysocolla, malachite and azurite.  It is opaque with a black streak and is brittle, commonly with a conchoidal fracture.  Tenorite is soft at ~3.5 (Mohs).  I have only observed massive and botryoidal tenorite; however, some localities produce small crystals (Monoclinic Crystal System).  It appears, from my reading, that visible crystals are only formed when tenorite is the product of volcanic sublimation (crystallized from gasses around volcanic vents).  In fact, the type locality for tenorite is around Mt. Vesuvius in Italy.

This year in Tucson I picked up another rather uncommon oxide containing copper—and iron, the mineral delafossite, CuFeO_2.    It is a combination of the cations cuprous copper (1+)  and ferrous iron (3+) and two atoms of oxygen (4-) or C2¹⁺Fe³⁺O^2-₂.  It is almost equal parts of iron and copper plus two parts oxygen, 1:1:2.  delafossite is black in color, has a hardness ~5.5 (Mohs), a black streak, a metallic luster, and is opaque.  Individual crystals are tabular to equant and at times appear as individuals on a matrix (often goethite); however, in many specimens (such as mine) the individual crystals are massed together in spherulitic masses.  In other instances, the crystals are essentially indistinguishable and massive.  As with cuprite and tenorite, delafossite occurs in the secondary zone of copper deposits (copper porphyry) as an oxidized mineral. It is interesting to note that the specimen of delafossite was once in the collection of Arthur L. Flagg, one of the best-know mineral collectors in Arizona (1883-1961).

Scattered spherical "clumps" of submillimeter delafossite crystals.

A bubble-like surface of delafossite with no visible crystals (at least at the magnification).  Perhaps cuprite is lower left quadrant. Width FOV ~1.0 cm. 

Light gray area is a mass of individual submillimeter delafossite crystals while the dark areas represent the spherical "clumps" of crystals.

A TANKARD OF TARBUTTITE

Day ? of the shelter-in-place has arrived and it is much like yesterday, and the day before, etc.  The only difference has been picking up pre-ordered groceries from the store.  The checkers just toss them in the trunk, and I wipe them down with disinfectant in the garage.  The major excitement comes from examining the “could not fill list.”  It was 70 degrees and sunny today while tomorrow brings subfreezing temps, snow, and lots of winds. Yuk.  But, plenty of books to read and there is always writing and looking at minerals.  So, compared to many people, especially those who have lost jobs, life is pretty darn good.

I pulled out a mineral specimen today from a previous Tucson show that has been on my “to do” since it is a somewhat rare phosphate mineral that has some nice crystals—tarbuttite [Zn₂(PO₄)(OH)] from the Kabwe Mines in Zambia, Africa.  Now if you would search for Kabwe Mines you would notice that: 1) Kabwe is Zambia’s second largest city; 2) Zambia was formally named Northern Rhodesia and colonized/governed by the British. It received independence in 1964; 3) it is one of the 10 most polluted places in the world (mining); and 4) a skull of early hominoid was discovered in 1921 and named Homo rhodesiensis but later assigned to Homo heidelbergensis. The cavern in the mine containing the skull was named the Bone Cavern and also produced animal bones cemented together by rare phosphate minerals (Notebaart and Korowski, 1980). Decades ago we learned about this find, the Broken Hill Man, in our anthro class.  The mines were previously named the Broken Hill Mines and that moniker is on my mineral label.  It also was in the collection of a German rockhound (I think) since the mineral was listed as tarbuttit (the e is missing).

Zambia is also famous as the site of Victoria Falls on the Zambezi River, a stream acting as the international boundary between Zambia and Zimbabwe (formally Southern Rhodesia).  It is considered to be the largest waterfall in the world due to its width of 5, 604 feet rather than its height (~350 feet).  The course of the River, and the Falls, seem controlled by faults and/or joints in the underlying Mesozoic basalts.

Tarbuttite come in a variety of pastel colors with the chromophores being copper or iron oxides; however, my specimen contains colorless and clear crystals (like most specimens).  The crystals are short prismatic to equant, often deeply striated, and appear either as individuals (rounded or with crisp faces), sheaf-like aggregates, or pseudomorphic crusts.  They have a vitreous/pearly luster, a hardness of around 3.5 (Mohs), and leave a white streak.  Crystals are transparent to translucent and have one plane of perfect cleavage.  Most rockhounds would identify this kind of nondescript mineral by knowing it came from a zinc mine and even then, I could confuse it with other rare phosphates.  It has only been identified at about 8 localities in the world.

 

Mass of translucent to transparent tarbuttite crystals on a vuggy gossen matrix. Width FOV ~1.5 cm.

Different crystal shapes of tarbuttite in above two photomicrographs.  Width FOV ~9 mm.

Spencer (1908) noted that at the type locality (Broken Hill #2 deposit) tarbuttite is was found in great abundance. Notebart and Korowski (1980) stated that in the late 1970s tarbuttite could be collected from the No. 2 open pit, and surrounding dumps. At this locality tarbuttite appeared as well-defined colorless crystals on masses of cellular goethite (iron oxide). I presume that my specimen was collected during this time period.

The lead-zinc deposits at Kabwe are hosted in Precambrian dolomites with mineralization of the sulfide ore deposits at around ~680 Ma (latest Precambrian but younger than the carbonate host rock). The major sulfide (primary minerals) are sphalerite (zinc sulfide), galena (lead sulfide), and pyrite (iron sulfide).  Most of the other minerals found at Kabwe are oxide minerals in the supergene zone above the primary minerals and are the best known and most collectable.  Among these are six rare zinc phosphates including tarbuttite (Kabwe is the Type Locality for tarbuttite, parahopeite, and zincolibethenite).

Now here is the question?  What are these toothpick crystals ranging from 1-2 mm in length.  Some are encased within tarbuttite crystals. They are cream colored with poorly defined terminations.  I thought about pyromorphite, hopeite, and parahopiete.

I have settled on quartz due to the hexagonal shape and crystal clear internal material (noted at the <---.)

The Kabwe Mine (the Broken Hill Mine) was discovered in 1902 and mining commenced in 1904 and continued until the late 1900s, but even today artisanal specimen exploration of the tailings continue.  Zinc was the major bread winner with a production of 1.8 million metric tons produced while lead came in second at 0.8 million metric tons. For those of us in the States, a metric ton is 2205 pounds, 205 pounds over our standard ton of 2000 pounds. 

The above information about the Broken Hill Mine was gleaned from a great article by Malcolm Southwood and others in 2019. That same issue of Rocks and Minerals also has an article on tarbuttite collected from the Skorpion Mine in Namibia. 

I thought it interesting to quote some of the original verbiage from Spencer (1908) as he originally described tarbuttite. Note: 1) the gentlemen-like language in the article; and 2) the use of laboratory tests that would seem rather primitive in today's modern world of electronic gizmos.

For the basic zinc phosphate to be now described I have proposed the name of tarbuttite, 1 after Mr. Percy Coventry Tarhutt, who himself collected, at the Broken Hill mines iu Rhodesia, several of the specimens which he has generously presented to the British Museum.

Chemical composition.--When heated in a bulb-tube, tarbuttite behaves quite differently from hopeite and parahopeite. At a high temperature it decrepitates slightly and gives off only a small amount of water. The material, when hot, is of a bright yellow eolour, which changes to pure white on cooling; the crystals are then opaque with a porcellanous appearance. This change in colour indicates that there is a separation of zinc oxide, and that tarbuttite is a basic zinc salt. Heated before the blowpipe on a loop of platinum wire, the mineral readily fuses to a clear, yellow bead, which on cooling crystallizes to an opaque, dark-grey bead ; fragments of this are doubly refracting. The mineral is readily soluble in dilute hydrochloric acid, and from this solution ammonia produces a bulky white precipitate which is readily soluble in excess of ammonia. Qualitative tests proved the presence of only zinc, phosphoric acid, and water ; cadmium is absent.

There is much more descriptive science in the article and I would suggest a peak at https://rruff-2.geo.arizona.edu/uploads/MM15_1.pdf.

In keeping with my alliteration theme on a not-to-exciting day, I am naming this posting a Tankard of Tarbuttite.  Does it mean anything?  Not really except for a wandering mind!

REFERENCES CITED

Cairncross, B., 2019, Tarbuttite, Skorpion Mine, Lüderitz District, Namibia: Rocks and Minerals, vol. 94, no. 2.

Notebaart, C.W. and S.P. Korowski, 1980, Famous mineral localities: the Broken Hill mine, Zambia: Mineralogical Record, vol. 11.

Southwood, M., B. Cairncross, and M.S. Rumsey, 2019, Minerals of the Kabwe (“Broken Hill”) Mine, Central Province, Zambia: Rocks and Minerals, vol. 94, no. 2.

Spencer, L.J., 1908, On hopeite and other zinc phosphates and associated minerals from the Broken Hill mines, North-Western Rhodesia: The Mineralogical Magazine, v. XV, No. 68.