VIVIANITE FROM FLORIDA SEDIMENTARY ROCKS AND BLUE DEAD BODIES

 

Vivianite is a hydrated iron phosphate mineral [Fe₃⁺⁺ (PO₄)₂-8H₂0] that is a crystal of many colors, and in fact, can change color over its lifetime. Freshly exposed vivianite is generally colorless but with time oxidizes to green to bluish green to blue crystals.  Continued oxidation of the iron from Fe⁺⁺ (ferric) to Fe+++ (ferrous)  will produce crystals so dark blue they appear black.  Many crystals have a vitreous luster although they can grade into pearly or dull specimens.  Colorless crystals are transparent while lighter colored specimens become translucent and massive specimens generally are rather opaque. As with the color, mineral streak ranges from colorless to various shades of blue. Vivianite is quite soft, ~2.0 or less (Mohs).  The best “showy” specimens have prismatic (elongated along the C Axis) or flattened/bladed (along the B Axis) crystals and often form in stellate cluster; however, there are a variety of other morphological forms.

Vivianite is thought to occur as: 1) as a secondary mineral in metallic ore deposits; 2) in pegmatites as an alteration product of primary phosphate minerals; or 3) as a mineral associated with the phosphate found in sedimentary deposits. However, Petrov (2008) noted the mineral is not characteristic of the oxidized zone but of “deep unoxidized levels of ore deposits.” Most vivianite specimens collected in the western states, or observed in rock and mineral shows, are secondary in nature or from the phosphate minerals in  pegmatites.  Collected specimens, when first exposed to sunlight and oxygen, are often a beautiful blue and prismatic along the C-axis.

Very rarely do Colorado rockhounds come upon vivianite collected from organically rich unconsolidated clays and other sediments/rocks (mostly Cenozoic in ages). In the U.S. most of these sedimentary vivianites come from the Central Florida Phosphate District (AKA Florida Platform) where iron and water, along with original phosphatic material, has allowed vivianite to form: Fe₃⁺⁺ (PO₄)₂-8H₂0. The original phosphorus is thought to have been derived from precipitation in marine waters, and from the skeletons/shells and the waste products  of animals living in these waters.

The basement rocks of the Florida Platform are a fragment of the African Plate that remained attached to the North American Plate when rifting occurred in the Jurassic and range in age from late Precambrian-early Cambrian to mid-Jurassic (Barnett 1975).

A sedimentary sequence rests uncomfortably on top of the basement rocks, and is composed of Middle Jurassic to Holocene evaporite, carbonate, and siliciclastic sediments. This sedimentary sequence is the result of deposition on the relatively stable, passive margin of the North American Plate (Scott, 1989, 2016).

During the Cenozoic concentrations of silt to sand-sized phosphate pellets, mixed with carbonates and clastic sediments, were deposited in shallow water environments over much of the Florida Platform, in a broad range of carbonate and clastic sediments. During the Miocene and Pliocene phosphate was particularly concentrated in several basins in the Central Florida Phosphate District and these were the areas where a major phosphate industry begin development in the late 1800s. By 1893, production had expanded to 1.25 million tons and Florida became the world's leading producer of phosphate for the next century. By 2015/2016 the U,S, had dropped to the 3^rd largest producer of phosphate behind China and Morocco and production had expanded from the “Eastern Phosphate Fields”  of Florida and North Carolina to the “Western Phosphate Fields” of Utah and Idaho. However, in 2021 Florida still produced ~75% of the U.S. production of ~24 million tons. The Eastern Field operations use open pit mining to extract the ore from Miocene and Pliocene sediments/rocks. The Western Fields mine phosphate from limestone in the Permian Phosphoria Formation (Scott, 2016).

A well-formed, terminated crystal of glassy and gemmy, blue-green, vivianite, ~4 mm in length, collected from Clear Spring Mine, Homeland, Central Florida Phosphate Mining District, Polk Co., Florida. Light patch is carbonate matrix. A backlight would show transparency. Collection of Art Smith 1980.

REFERENCES CITED

Barnett, R. S., 1975, Basement structure of Florida and its tectonic implications: Gulf Coast Association of Geological Societies Transactions, Vol. 25.

Hurst, M. V. (Ed.), 2016, Central Florida Phosphate District Third Edition: Southeastern Geological Society Field Trip Guidebook No. 67.

Scott, T.M., 1989, The Geology of Central and Northern Florida with Emphasis on the Hawthorn Group, in Scott, T.M., and Cathcart, J.B., AGU 28th International Geological Congress, Field Trip Guidebook T178.

Scott, T. M., 2016,  Geologic overview of Florida in Hurst, M. V. (Ed.), Central Florida Phosphate District Third Edition: Southeastern Geological Society Field Trip Guidebook No. 67.

Virtually everything you might want to know about Florida phosphate may be found in the Hurst guidebook referenced above and available as a PDF file: http://www.segs.org/wp-content/uploads/2010/01/SEGS-Guidebook-67.pdf

 

AND NOW FOR THE REALLY INTERESTING STORY FROM CHRIS DRUDGE October 25, 2016 at: The Vivid Blue Mineral That Grows on Buried Bodies and Confuses Archaeologists - Atlas Obscura

IN 1861, a railway engineer by the name of John White passed away, was buried in a cast iron coffin, and began a slow transformation from White to blue.

The explanation for this spooky color change, which has occurred on numerous occasions all over the world, lies in the composition of the human body. Among the molecules contained within us is phosphate, a central phosphorus atom bound on four sides to atoms of oxygen. Phosphate is present in the hard bits of bones and teeth (as part of the mineral hydroxylapatite), helps hold together strands of DNA and RNA, and is used by cells to store and move energy around as well as to organize their many protein-driven activities.

If a dead person ends up buried somewhere waterlogged, lacking in oxygen, and loaded with iron, the phosphate leaking from their decaying remains can slowly combine with the iron and water to form a mineral called vivianite. It starts out clear and colorless, but will rapidly turn progressively darker shades of blue upon exposure to air as the iron within it reacts with oxygen. The formation of vivianite (also known as blue ironstone) is helped along by bacteria which act to dissolve iron out of soil and phosphate out of bodies while also directing the growth of the blue crystals. 

In the case of Mr. White, in keeping with the styles of the time, his coffin had a glass window installed in the front so his face could be seen by mourners when the lid was shut. At some point after burial, the glass had broken, allowing groundwater to seep inside and react with the cast iron coffin and phosphate-rich body. The end result was a corpse surround by blue vivianite crystals, revealed when the coffin was exhumed as part of an archaeological rescue excavation over a century after being buried.

 

 

THEISITE: Just because you don't understand it doesn't mean it isn't so.

I am always on the lookout for funky and sort of quirky uncommon to rare minerals. My small mineral collection has numerous specimens that I purchased due to the facts that I did not recognize the name, and it was cheap. Anything coming off of a dusty shelf with an older label was a bonus. An extra, extra bonus was created if the new mineral was collected in Colorado. And a three-level bonus appeared if the mineral came from near Tuckerville, Colorado, a town, well really a former town now inhabited by ghosts. After purchasing a three-level bonus mineral I didn’t have the slightest idea about the location of Tuckerville until I noticed it was close to Vallecito Reservoir. That particular body of water, on the Pine River, is located about 18 miles northeast of Durango. I have camped there twice in absolutely beautiful USFS campgrounds and spent the time fishing rather than exploring back roads. Tuckerville is then located about 12 miles northeast of the Reservoir on FS 2274 or Middle Mountain Road, a winding road that feels better in a 4-wheel drive pickup than a low-slung passenger car. The elevation is ~ 10,600 feet. After speaking to the ghosts of “almost nothing left” Tuckerville, rockhounds must take a hike (400 feet elevation gain) on the established “jeep trail” to reach the old mines of Tuckers Tunnel or Tuckerville Prospects. Evidently the tunnel has collapsed as have other adits. Mineral collectors who made it this far have zeroed in on what remains of the Tunnel dump. MinDat lists 31 valid mineral species collected in the dump and noted the Tunnel dump as the Type Locality of theisite [Cu₅Zn₅(AsO₄,SbO₄)₂(OH)₁₄].

WORDS OF THE DAY

Funky Mineral: Theisite

Ghost Town:  Tuckerville

New Geological Term to Learn:  Fahlore Deposits

There is not much to say about the Tuckerville Prospects except I regret not being able to visit the locality (at the time of camping at Vallecito I was chasing fossils). Very little information, at least that I could locate, is published on the mining area. Certainly, the best publication is a Rocks and Minerals article by Haynes and Paul Hlava (1998). In addition, Williams (1982) described theisite as a new mineral in Mineralogical Record; however, I could not locate a copy of that article but did find the abstract.

Google Earth© image of the location of Tuckerville (nothing to see on image) and the Tuckerville Prospects.  The winding road comes north from Vallecito Reservoir.

According to Haynes and Hlava (1998) the Tuckerville Prospects are part of the Cave Basin Mining District where in 1913-1914 speculators and investors were overly optimistic about future production of copper, silver, and gold—many claims were filed but production was minimal. As best I can determine in adding figures together, the Cave Basin mines, mostly the Mary Murphy, Holbrook, and Silver Reef, produced a tad less than 100 ounces of gold, ~270 ounces of silver, ~2900 pounds of copper, and ~1700 pounds of lead---all from ~120 tons of ore shipped (via animal drawn wagons or mule trains????) down the mountain to an unknown processing plant. Mining was sporadic from 1913 to 1936. The above production figures are from Schmitt and Raymond (1977) and Steven and others (1969).

I may be missing something but have been unable to locate base metal production figures for the Tuckerville Prospects (the above production figures are from the entire District).  However, it must have been minuscule. The minerals listed by MinDat do not include silver or gold; however, some minerals do include copper, mercury, zinc and maybe a grain or two of galena (lead). Theisite was discovered in 1980 at Tucker Tunnel by two geologists, N.J. Theis and Michael Madsen (Theis and others, 1981), as they tromped through the area looking for uranium—evidently there are some rocks that excite a Geiger Counter, perhaps uraninite and/or zeunerite, as Haynes and Hlava stated, “the prospect [Tuckerville] is radioactively anomalous (up to 700 gamma counts per second).” Steven and others (1969) noted that “base and precious metals in the Cave Basin District were replacement deposits in lower Paleozoic sedimentary rocks”—perhaps the Ouray of Leadville formations.

Now down to the new mineral from Tucker Tunnel—theisite, a copper zinc arsenate antimonate. We know the chemical makeup of the mineral due to analyses by X-ray Powder Diffraction and Electron Microprobe studies. Unfortunately, I don’t have either gizmo in my office.

Visually (with a microscope) theisite is very difficult to identify, especially for an ole plugger like me. First of all, specimens are usually quite small (mine are really, really tiny) and rarely occur as crystals but as crusts, spherical aggregates or simply individual spheres, cleavage plates, micaceous plates, or just plain globs. The color is some sort of blue + green: greenish blue, turquoise-green, turquoise-blue, pale green, or pale blue. Specimens have a pearly luster and are very soft (MinDat states 1.5 Mohs).  I found it very difficult to identify my small specimens and if not for the collection and identification by David Shannon I could have guessed any number of copper zinc minerals.

Two dark green spheres of theisite and two lighter green spheres of "your guess." The dark mineral is a manganese oxide. Width FOV ~4.0 mm. 

Green to blue green theisite spheres or cluster of spheres in and around a vug. Width FOV ~4.0 mm.

Scattered green to blue green theisite spheres or cluster of spheres. Width FOV ~3.0 mm. 

Clear gemmy crystals of platy hemimorphite with black manganese oxide. Width FOV ~2.0 mm. 

MinDat pointed out that theisite was a rare secondary mineral in fahlore deposits. Well, that piece of info rattled my brain and sent me scrambling. The best I could do with an understanding definition of fahlore was from Wikipedia: Fahlore refers to an ore consisting of complex sulfosalt minerals (a metal + semi-metal + sulfur) and in the case of theisite the mineral is formed due to oxidation of a mineral(s) in the tennantite--tetrahedrite solid solution series.

Just because you don't understand it doesn't mean it isn't so.

            Lemony Snicket

REFERENCES CITED

Haynes, P.E. and P.F. Hlava, 1998, Mineralogy of Tuckers Tunnel: Tuckerville, Hinsdale County, Colorado: Rocks & Minerals, vol. 73, no. 5.   

Schmitt, L. J. and W. H. Raymond, 1977, Geology and mineral deposits of the Needle Mountains district, southwestern Colorado: U.S. Geological Survey Bulletin 1434.

Steven, T. A., L. J. Schmitt Jr., M. J. Sheridan, and F. E. Williams, 1969, Mineral resources of the Sun Juan primitive area, Colorado: U.S. Geological Survey Bulletin 1261-F.

Theis, N. J., M. E. Madsen, G. C. Rosenlund, W. R. Reinhart, and H. A. Gardner, 1981, National uranium evaluation, Durango quadrangle, Colorado, Grand Junction, Colorado: Bendix Field Engineering Corp.

Williams, S. A. 1982, Theisite, a new mineral from Colorado: Mineralogical Magazine, vol. 46.

PERHAMITE, A RARE PHOSPHATE FROM MAINE

 

Although I enjoy collecting minerals, especially phosphates, in the pegmatites of the Black Hills of South Dakota I often wish the rocks of Maine were a wee bit closer to my home in Colorado! Since the journey is more than a day trip I am left with purchasing specimens found at rock and mineral shows, a good alternative. Interestingly, to an ole softrocker like me who spent most of his professional career looking for fossils in Mesozoic and Cenozoic outcrops, rocks of Maine generally lack exposures of these ages except for scattered small igneous intrusions and dikes of Mesozoic age. Maine rocks are Precambrian and Paleozoic (mostly Cambrian through Devonian) in age with a covering of unconsolidated sediments left behind by Pleistocene glaciers. The latter seems to support a heavy growth of trees and undergrowth that often inhibits the discovery of the underlying bedrock. However, there are many “stone” quarries around the state that have allowed geologists and rockhounds to collect a bonanza of interesting minerals and gems.  Geology.com noted that the first commercial gemstone mine in the U.S. dates back to 1821 when gem tourmaline was collected near Paris in a pegmatite on a hill known as Mt. Mica.  That mining has continued to the present. Most Maine collecting localities are in pegmatites scattered across the state (especially in the counties of Oxford, Androscoggin, and Sagadahoc ---AKA Maine Pegmatite Belt) that offer rockhounds and geologists opportunities in both commercial mines, such as Poland Mining Camps, and in abandoned quarries.  In addition, there is the Maine Mineral and Gem Museum in Bethel containing stunning displays, and also housing the Mineralogy, Petrology, and Pegmatology Research Group. The latter entity “focuses on exploring the pegmatites of Maine and their associated minerals.”

One of the most studied pegmatites in Maine is the Emmons Pegmatite found on Uncle Tom Mountain in Oxford County where beryl and other minerals were found in the early 1900s and first mined for feldspar in the 1930s; however, that venture was rather short-lived due to the long distance of the mine from a processing plant.  Early mineral collecting enthusiasts then started extracting beryl and ultimately collected about 5000 carats of gem morganite (pink beryl); however, specimen mining did not really take off until the late 1900s.; ---see the complete collecting and mineral story in Falster and others (Rocks and Minerals, v.94, no.6).

One of the interesting minerals from the Emmons that popped up in rummaging through my collection (from a purchase several years ago) was the phosphate perhamite [Ca₃Al_7.7Si₃P₄O_23.5(OH)_14.1-8H₂0], a specimen originally collected by Micromounter Hall of Fame member Gene Bearss.  The mineral is a rare calcium aluminum silico-phosphate that usually is found as isolated small spherules in late-stage pegmatite vugs. The Bearss specimen (photo below) shows the common morphology--a spherical aggregate of subvitreous hexagonal plates. Falster and others noted that perhamite from the Emmons pegmatite ranks among the finest examples of this species. Width of the spherule is ~1.0 mm.

SILVER AT MT. SHERMAN TUNNEL MINE

I wasn't born with a silver spoon in my mouth in Kansas City but I was born with a love for nature and the outdoors in a poor central Kansas farming community.

In the Mosquito Range of central Colorado lies one of the state’s most climbable 14ers, Mt. Sherman (14,043 feet). The common way to access the peak hiking trail is a gravel road leading west from near Fairplay to a parking area at the old Leavick Mill. Since Sherman was only the second 14er that I summited in my early hiking days, that was the route I chose.  However, during my next adventure to the peak I wanted to try something different (and more difficult) and that was coming in from the west via Leadville and Iowa Gulch.

For a geologist the upper part of  the Iowa Culch  trail goes near a number of old mines and one mine that may or may not be somewhat active, but still under claim—the Sherman Mine or the Sherman Tunnel Mine.  The mine may be seen from a distance as it is above timberline (12,200+ feet) at the base of a large cirque (Iowa Amphitheater). According to MinDat.org the mine opened in 1968, closed in 1970, reopened in 1975 and then closed again in 1982 and produced around 10 million oz. of silver, and evidently some copper, gold, lead and zinc freed from chalcopyrite, sphalerite, smithsonite, and galena.  Like almost all mines in the area the minerals were hosted in a fault-controlled karst system developed in the Mississippian Leadville Formation with mineralization occurring in the Permian.

The Mine is probably best known for producing a rich array of secondary minerals prized by rockhounds including the gangue mineral golden barite, and the carbonates rosasite (copper and zinc), azurite (copper), smithsonite (zinc), aurichalcite (zinc and copper), and cerussite (lead). Azurite and barite specimens were described in a posting on November 20, 2020.

Now two years later I located a small specimen of rosasite and silver that I had sort of not noticed in my collection. Rosasite [(Cu,Zn)₂(CO₃)(OH)₂] is a rather common, interesting carbonate with the copper-zinc ration about 3:2 and forms in the oxidized zone of ore deposits containing copper and zinc. It usually occurs as a botryoidal or spherulitic crust with colors ranging from blue to blue-green to green. The color and the spherulitic nature of the crust make rosasite somewhat easy to identify. The accompanying native silver is a silver white color with some tarnishing to a black (just like “silverware” utensils).

Spherulitic crust of rosasite with a small piece of silver-white native silver along with tarnished (nondescript) gray masses. Wirth FOV ~4mm.

My mountain climbing days are over, but I shall always cherish the numerous expeditions to the many mines in the area and the exhilaration of hiking the nearby 13ers:  Mt. Sheridan (13,748), Peerless Mountain (13,348), Horseshoe Mountain (13,898), and Gemini Peak (13,951).

Everyone wants to live on the top of the mountain, but all the happiness and growth occurs while you're climbing it.  Andy Rooney

MUSCOVITE: BACK TO THE BLOGOSPHERE

 Well, it appears that I have been off the Blogosphere for several weeks and need to get my writing in gear. Not really nifty excuses but: 1) the house/home needed some repairs in order to prepare for cold weather and winter; 2) do you know how many colorful maple leaves are on three mature trees (and they all need to pitter-patter down to the lawn); 3) receiving a letter from the state department of revenue with their interpretation (not mine) of my 2021 income tax; 4) construction of three power point programs (each an hour long) for meeting/conference presentations (done) is time consuming. Fun, but a real suck of time.

So, I just finished reading a Blog Posting by Hollis over at In the Company of Plants and Rocks and it was a barn burner about the geology of the House Range in the West Desert of Utah.  I could tell that the author put in tens of hours of observing, reading, and writing to construct a fine piece of work. But I am going to start with something very simple. Two interesting photos of muscovite, one from Brazil and the second from South Dakota!

                                        Brazil. Width FOV ~4.0 cm.

                                                South Dakota. Diamond Mica Mine. Width FOV ~2.5 cm.                              

Muscovite [KAl₂(AlSi₃O₁₀)(OH)₂] is one of those minerals that was easy to identify in my beginning geology course. It was the soft (~2.5 Mohs),  “light colored” (pale yellow to pale light brown to pale green to silver white) mineral that could be split into very thin, transparent, elastic sheets; it had perfect basal cleavage. A similar dark colored (iron rich) mineral was always labeled biotite.  These two minerals, commonly referred to as mica, were essentially freebies on the lab tests. However, at times the class examined very fine-grained river sand, or perhaps a piece of sandstone or gneiss and it became tougher to identify the shiny, shimmering flakes as muscovite.

                             

A specimen almost completely composed of muscovite books, quarter for scale (lower).  Collected a few miles west of Custer at an abandoned quarry.

In areas of igneous and metamorphic outcrops these weathered and eroded flakes in river sands shimmer with a slow current and clear water and are a major cause of “gold fever.”  Tourists and other visitors to Colorado see these shimmering flakes when the kids bound out of the car and head to the stream and believe they have hit the jackpot. Alas, no shiny gold but just tiny flakes of muscovite.

Muscovite is easily identified “in the field” by its formation of massive crystalline books found in many types of igneous and metamorphic rocks but especially prevalent in granite and granitic pegmatites.  The larger the mineral grains, as in pegmatites, the larger the muscovite books. Roberts and Rapp (1965) described many large muscovite crystals from the Black Hills of South Dakota, “one of the most productive [mica] districts in the United States”: 1) books of muscovite as much as three feet across from the Crown Mica Mine; 2) a book of muscovite three feet wide, four feet long and eight inches in thickness from the White Spar Mica Mine; and 3) a crystal of mica weighing 36 pounds from the Lake Mica Prospect.  MinDat listed 37 different varieties of muscovite, most were due to different cations appearing in the crystal structure. Some of these cations impart “colors” to muscovite such as in fuchsite, a greenish chromium-bearing variety.

Muscovite is also a member of the Mica Group, a “term for the sheet silicates that can be parted into flexible or brittle sheets”---as defined by MinDat. The data base also listed 70 members of the Group although not all are “officially” valid minerals.  For example, zinnwaldite, a somewhat common “mineral” found in rocks associated with the Pikes Peak Batholith is now discredited and placed as a dark mica containing lithium found in the siderophyllite-polylithionite series (see Blog posting November 24, 2013). Lepidolite, a pink to light purple Mica Group member has been discredited and is now assigned to the polylithionite-trilithionite series (see MinDat). Rock/mineral shops, and purveyors of rock/mineral trinkets, found across the U.S. have lepidolite “for sale.”  In fact, “lepidolite” collected from the Black Hills was the first mineral specimen I purchased as a kid. 

Lavender "lepidolite" collected from Bob Ingersol Mine, Black Hills. Color probably due to manganese.  Width about 5 cm.

Rose or pink or lithium muscovite collected from the Harding Mine, Taos County, New mexico. As Rob Lavinsky noted on Mindat, "on close inspection, you can see these muscovite crystals are translucent to transparent. They are actually masses of sheety crystals stacked densely together." The color is probably not due to lithium but to manganese and iron. Width of crystal mass ~1.9 cm.

OK, back to my simple photos of muscovite.  Most “books” of muscovite that are commonly found by rockhounds have a hexagonal shape in a cross-sectional view. That, along with its tabular form, elasticity, and transparent cleavage sheets, is usually enough to identify the mineral.  However, one of the more collectable micas in the Black Hills comes from the Diamond Mica Mine in the Keystone Mining District. Here the single crystals are, you guessed it, diamond shaped.

Muscovite crystals collected from the Diamond Mica Mine, Width of each crystal ~3.2 cm.

Muscovite crystal collected from the Diamond Mica Mine (Courtesy of Dakota Matrix). Note sharp crystal face boundaries.

Galleries.com noted that muscovite tabular crystals have a prominent pinacoid termination, that is the crystal has a pair of opposite parallel faces. The diamond shaped books have four dominant crystal faces with two pairs of opposite parallel faces. If another pair of parallel crystal faces form, then the books have a hexagonal shape. However, the diamond shaped muscovite from the Diamond Mine varies in shape and pinacoid terminations. Notice in the lower figure above, lifted from DakotaMatrix.com, the sharp corners of the diamond. Compare that with my specimens from the mine where an additional two parallel faces occur on the diamond.  Although the specimens are coarsely diamond shaped, the crystal has six faces. As I understand the situation (a stretch), muscovite is Monoclinic; however, the symmetry is not easily observed. The diamonds simulate Orthorhombic symmetry with prism faces meeting at ~ 60 degrees, The six-sided forms have prism angles of ~120 degrees and appear to have Hexagonal symmetry. I have never pretended to be a crystallographer and my low pay grade does not allow me to speculate on the mechanics of those designs! Crystal Systems and Crystal Classes are one of the reasons I became a paleontologist!

So, just when I think that muscovite is “easy” to identify I notice that the Handbook of Mineralogy throws the proverbially wrench into the equation:  muscovite is also described as “stellate aggregates, plumose, globular, scaly, granular, compact and massive.” One needs to consult MinDat to locate photos of these different habits.

Muscovite with twined crystals forming yellow five-pointed (or less) stars. Most star specimens come from pegmatites in the Jenipapo District, Minas Gerais, Brazil. FOV width ~4.0 cm.

Of these forms, the stellate aggregates, or star muscovite, are perhaps the most collectable, appealing, and attractive of the many habits of muscovite. Star muscovite involves twinning of the crystals in a manner that remains confusing to me.  I spent several hours reading the literature and my noggin still does not comprehend:  Twins in micas are difficultly identified due to mica’s hexagonal pseudosymmetry. In this paper, we present an electron backscattered diffraction analysis to identify twins in the muscovite… A trilling twin with twin law <310>/{110} is common in the muscovite. A six-couplet twin consisting of two trilling twins related by twin laws <110>/{130} and <001>/{001}(or <100>/{100}) has been discovered (Zhao and others, 2019). Remember I am a softrocker!

Regardless of my snarky comments I learned much from this little exercise, not the least of which is that a tremendous amount of literature is available for such a common, rather nondescript, easy-to-identify mineral.  I certainly did not realize that muscovite is such a complex mineral. As such I fell into the habit of pursuing the literature over a ten-day period and therefore did not reach my goal of just getting something into the Blogosphere. Oh well, life is interesting.

One item I did not miss out on during this final exam study (at least it felt like such) was observing the full moon, known as the Beaver Moon, on the evening of November 7. Officially the full moon, the peak illumination, was very early on the morning of November 8.  Unlike many moon watchers I was sound asleep at 4:00 am and as such missed the lunar eclipse and the Blood Moon phase. This reddish hue happens when the moon is completely in the earth’s shadow and the rays from the sun are blocked.  Over the course of several hours the full moon goes from a bright white ball to the copper hued object.  I probably should have got my derriere out of the sack and observed the event as the next full lunar eclipse is something like three years distant. However, I caught the eclipse several times on the magic of the Internet and did watch the previous lunar eclipse in May 2022 (the Super Blood Moon as pushed by the media) although it bounced in and out of the clouds in later stages. At any rate, lunar eclipses are great astronomical events.

As I daydream through my life and think of these astronomical events, I remain fascinated by members of the ancient Mesoamerican civilization of Central America. They built their pyramids, ball courts, palaces, temples, and other structures in accordance with astronomical events and positions of the sun, moon, planets, and stars over the course of a year. Of course, as a person of Scandinavian descent I am partial to the views of the Norsemen who believed that a large wolf, Fenrir, was constantly chasing the sun and at times got lucky and caught the orb and the lights go out--a lunar eclipse.

Bound of Fenrir. Dorothy Hearthy (1909). Public Domain.

REFERENCES CITED

Roberts, W.L. and G. Rapp Jr., 1965, Mineralogy of the Black Hills: South Dakota School of Mines and Technology, Bull. No. 18.

Zhao, Shan-Rong, Chang XU and Chuan Li, 2019, Identification of twins in muscovite” an electron backscattered diffraction study: Zeitschrift fur Kristallographie—Crystalline Materials 234(5). DOI: 10.1515/ZKRI-2018-2139