BLACK DIAMONDS FROM MICHIGAMME

 It is tough to be a diamond in a rhinestone world! Dolly Parton

 I suspect that most rockhounds have a garnet or hundred in their collection. These silicate minerals have been used as gemstones for millennia, as well as having numerous uses in industry. Collectors love garnets since they are usually easy to identify by their red to reddish brown color (or green or black or pink or violet), by their hardness of ~6.5 to 7.5 Mohs, their crystal habit that is often 12 sided rounded dodecahedrons, and their occurrence in high temperature metamorphic rock like schists, igneous rocks such as granite, and detrital sediments such as sands. The more serious, or even semiserious, collectors define the general garnet formula as X₃Y₂(SiO₄)_3.  This formula is then used to differentiate the 1) Pyralspite Garnets where aluminum fills the Y site: the iron aluminum Almandine, the magnesium aluminum Pyrope, and the manganese aluminum Spessartine and 2) the Ugrandite Garnets where calcium fills the X site: calcium iron Andradite, the calcium aluminum grossular, and the calcium chromium uvarovite. These two major groups are actually solid solution series with intermediate garnet varieties and several mixed cation varieties. Chemists also experiment with several synthetic varieties of garnets where new elements substitute  for silicon in SiO₂ part of the chemical formula.

The fat, quarter-size crystal I want to describe in this post is not one of the common, shiny, dark red, iron-rich, well-defined dodecahedrons of almandine---although it used to be! The specimen was collected from the Michigamme Mine in Marquette Michigan and that locality provided the clue to its description. Greenish black to black chamosite has pseudomorphed the classic dodecahedral crystal of almandine. 

 

A 12 sided dodecahedron of chamosite ps. almandine. Width FOV 1.9 cm.

Chamosite is the iron rich member of the chlorite group of minerals, a hydrous iron aluminum silicate (Fe²⁺)₅Al(Si,Al)₄O₁₀(OH,O)_8.  As a sheet silicate it has a laminar shape similar to the mics. These sheets are usually greenish gray to brown to greenish black in color and are translucent to transparent, and soft (~3 Mohs), and flexible. The luster is usually dull to pearly. Chamosite is in solid solution with clinochlore, its magnesium analog, and both commonly occur in sedimentary iron formations.

 The chlorites, including chamosite, are part of the “clay minerals”, and as such, have very tiny crystals that are often earthy in appearance. In my specimen chamosite has altered, disrupted, and changed the internal lattice and structure of the almandine; however, the external shape, a dodecahedron, has remained. It remains beyond my pay grade to understand exactly “why” or “what caused” the almandine to be replaced by chamosite.

The most famous of the chamosite ps. almandine specimens have been found in the dump piles of the Michigamme Iron Mine, "Marquette Iron Range," in Marquette County, Michigan. Termed “Black Diamonds” by the miners, these very hard specimens were a pain in the derriere for the ore crushers. However, historical accounts noted that local entrepreneurs sold the black diamonds to visitor and tourists, especially those on the trains stopping at the Michigamme Railroad Depot. A note on my specimen stated it was collected ca. 1900.

 Location of the Marquette Iron Range. Public Domain map courtesy of W. F. Cannon, USGS.

The Michigamme Mine, from ~1872 to 1905, produced perhaps, I don’t have good figures, a million tons of iron ore from the Proterozoic Negaunee Iron Formation and the overlying Michigamme Formation. The cherty ore pay rocks were hematite-rich with secondary magnetite and grunerite. I also saw a note that recent Michigan road construction crews have covered the dump piles of the mine with a new road. The reporters were lamenting the loss of again collecting these magnificent black diamonds.

It is more fitting for a man to laugh than to lament over it.

                        Seneca the Younger

 

Almandine garnet crystals on gray-green schist. Public Domain photograph courtesy of Didier Descouens.           

 

CHASIN' THE BLUES WITH JAKE, ELWOOD, KEVIN, BILL, AND BOB

 THIS POST WAS ORIGINALLY PUBLISHED 3-4 YEARS AGO AND HAS BEEN IN DRAFT FORM FOR AN UNKNOWN TIME. IN SCROLLING THROUGH MY POSTS I DISCOVERED IT AND THOUGHT IT NEEDED TO SEE THE LIGHT OF DAY.

Sprays of blue brochanite on quartz terminations (photomicrograph). Width FOV ~1 cm. Photo: Mike Nelson

 

And the idea of just wandering off to a cafe with a notebook and writing and seeing where that takes me for a while is just bliss. J. K. Rowling

Movie Poster, Public Domain, photographer unknown.

In this time of the Covid-19 pandemic and self-isolation my mind wanders, as do the minds of several rockhound friends. That wandering activity is not a “bad thing” as most of us have some degree of ”pandemic depression.  Listen to the advice of newscaster Diane Sawyer,  I've always found a cure for the blues is wandering into something unknown, and resting there, before coming back to whatever weight you were carrying. Between wandering I try to keep busy with other chores (I am tired of raking leaves) and activities.  I read a new book about every three days or so, play with the minerals, devour the newspaper, write letters to the editor (few are published), write/read several hours a day, watch a little TV (mostly older “happy” movies with such phrases as: Jake: That Night Train's a mean wine) , exercise a little, and listen to the oldies music channel : Elwood: What sort of music do you usually have here?  Claire: Oh we got both kinds, We got country, AND western. As you can probably surmise, I have a weird sense of humor and enjoy watching the Blues Brothers: I have four fried chickens and a coke. OK you need the see the two movies to understand the humor of Jake and Elwood!

 

Kyanite, a metamorphic aluminum silicate from Brazil. Photo: Kevin Witte.

Blue halite from the Delaware Basin, New Mexico.  Cube ~2.5 cm. X 2,5 cm. Photo: Mike Nelson.

 

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. Photo: Mike Nelson.

 

My days are not strenuous but are not too exciting either; however, we have food and shelter and family wellness and for this I am happy.  And, as you might suppose I am “retired” with Social Security and do not hold an actual working position and that certainly skews my activities and thinking.  One of the good things about my life is that I am learning much, not only about minerals, but about the world in general, how a virus operates, a new word every day, how bars form a significant part of our social wellbeing, about economics as the price of groceries heads upwards while gasoline trends down, and how scientists are taking a bum rap with this pandemic.  Personally, I am waiting for scientists to conquer the Covid-19 pandemic.

 

Blue-green microcline var. amazonite collected Lake George area Colorado (top), Galway, Ireland (bottom). Photo: Bob Landgraft, bottom; Kevin Witte, top.

 

Lapis Lazuli, metamorphic rock composed of sulfur-rich hauyne (in the Sodalite Group) with lesser amounts of calcite and pyrite.  Photo: Kevin Witte.

 

 

Lazulite a magnesium, iron, aluminum phosphate from Rapid Creek, Yukon, Canada. Width of crystal ~3 mm. Often confused with Lapis. Photo: Mike Nelson

But as I said, my mind tends to wander and this week, for some strange reason, my thoughts moseyed over to the color blue and all sorts of items popped into my mind, like: what is your favorite color?  For me it is blue.  As John Lennon once sang, “The sun is up, the sky is blue” or Judy Garland’s “Somewhere over the rainbow. Skies are blue.” Thinking about blue: 1) there are more songs with blue is the lyrics than any other color; 2) blue is the only color to have a genre of music named after it, The Blues; 3) if one of our 50 states primarily votes for the Democrat presidential candidate, it is a “blue state” 4) and so it goes. As for music:

Blue

Oh, so lonesome for you

Why can’t you be blue over me

Blue

Bill Mack but a big hit by LeAnn Rimes

 

Well it's one for the money, well it's two for the show

Well it's three to get ready, now go, cat go

But don't you step on my blue suede shoes

Well you can do anything but lay off of my blue suede shoes

Carl Perkins or Elvis Pressley

 

Devil with the blue dress, blue dress, blue dress,

Devil with the blue dress on

Mitch Ryder

 

Blues stay away from me

Uh-uh-uh, blues why don't you let me be

I don't know why you keep a-hauntin' me. and I guess that's why

Delmore Brothers

 

Got the blues, got the blues

Got the blues, got the St. Louis blues

Louis Prima

 

 

A poster, source unknown, advertising the Delmore Brothers.

 

Namibia

Namibia.

Lake George area, Colorado.

Fluorite, calcium fluoride. Italy. Photos above: Kevin Witte

Fluorite, calcium fluoride. Photo: Bob Landgraft.

What about your favorite Blues genre or blue in the lyrics song?  Do rockhounds have a favorite?  Well, as an ole rock and roller like me (my age is certainly showing) Carl Perkins and Mitch Ryder are tough to beat.  But my all-time favorite is the Delmore Brothers, “Blues stay away from me.”  The music is very haunting (probably because of the tenor four string guitar and the harmonica of Wayne Raney, but it brings back memories of my youth when Saturday night dances were scattered across the rural areas of Kansas. Those dances usually presented a “big band” sound, or “hillbilly” music; rock and roll generally was confined to high school dances.  In the days before cable TV high school or “town team” sporting events, and local dances were the major sources of entertainment in rural parts of our country. Yea, I know very few readers have heard a recording by the Delmore Brothers!  But consider they were stars of the Grand Ole Opry in the 1930s and wrote more than 1000 songs. Perhaps Bob Dylan summed it up best: “The Delmore Brothers, God I really loved them! I think they’ve influenced every harmony I’ve tried to sing.”  So, there you know some of my strange secrets! Take a peek at this youtube recording:  https://www.youtube.com/watch?v=YUk9UDoVyKk

 

Aquamarine, Pakistan. Photo: Kevin Witte.

Aquamarine, Namibia.  Photo: Kevin Witte

Maybe you have a favorite "blue" movie?  Who could forget The Blues Brothers--It's 106 miles to Chicago, we've got a full tank of gas, half a pack of cigarettes, it's dark and we're wearing sunglasses. Hit it.  Perhaps Blue Velvet, The Blue Lagoon, Blue Hawaii, or the IMAX film the Blue Planet? But again, I am showing my age.

 

Plumbogummite with pyromorphite, China.  Photo: Kevin Witte.

Barite, Hartsel, Colorado.  Photo: Kevin Witte.

So, what about your favorite blue mineral?  I presume a large segment of the rockhound population would immediately state azurite, the copper carbonate. Others might spout turquoise or zoisite (tanzanite), opal, aquamarine, or numerous others. So, it popped into my head, since we do not have club meetings, ask members of the CSMS to send me photos of their favorite blue minerals.  I was expecting about 50 bored rockhounds to flood the emails! But it appears that most members must be occupied with other important activities and I sincerely thank Kevin Rockhounding the Rockies Witte, the guy who knows about fluorite Bob Landgraft, and Mr. Lapidary Tool Man Bill Kern.  But most of all I thank John Emery, the fantastic Pick & Pack Editor for allowing me to add rather frivolous material to a mostly serious newsletter.  However, the activity perked up my mind and perhaps readers might find a little humor to help put a damper on “pandemic fatigue”.  So, thanks John.

   

Azurite with malachite collected Arizona 1980s.  Photo: Bill Kern.

Quartz, enhanced (radiation?) to form "blue Quartz."  Photo: Bill Kern.

Azurite with Malachite, Cuba, New Mexico.  Photo: Kevin Witte.

I have espoused my views on blue minerals with numerous Blog postings and today have a couple of new, blue, copper arsenates: guanacoite and arhbarite.  You aren’t familiar with them? Neither was I until I found them in a dusty drawer of a small rock and mineral store and started reading.

Arhbarite, a hydrated copper magnesium arsenate [Cu₂Mg(AsO₄)(OH)₃], 
gets its “strange” name from the Type Locality in Morocco, the Arhbar (orAghbar) Mine.  It usually has a dark blue color, a vitreous to sub-vitreous luster, a blue streak, and often forms as botryoidal cluster of radially grown crystals.  However, at times the crystals are so tiny that the mineral appears massive. Arhbarite forms in the oxidized zone of polymetallic ore deposits due to percolating hydrothermal fluids and is usually associated with other copper arsenates such as conichalcite and guanacoite.  Arhbarite is a rare mineral only found in two localities, the Type and in Guanaco in Chile.

In fact, the “strange” name for the second mineral, guanacoite, comes from its Type Locality in the El Guanaco Mine (Atacama Desert, Chile).  The mine produces gold (primary commodity), silver, and copper (chalcocite, bornite, enargite, and covellite) from Eocene rhyolite.  It is both a subsurface and surface mine. In addition, the Mine is a source for numerous and colorful blue and green copper minerals, including copper arsenates.

Dark blue massive arhbarite vug (top) with light blue guanacoite  prismatic and bladed crystals (bottom).  Length (vertical in photo) of both minerals ~3 mm. Photo: Mike Nelson

Closeup of above photomicrograph. Photo: Mike Nelson.

Dark blue arhbarite surrounded by prismatic crystals of guanacoite.  Maximum width of blue mass ~1 mm. Photo: Mike Nelson. Guanacoite is similar to arhbarite in that it is a hydrated copper magnesium arsenate except it has additional water [Cu2Mg3(AsO4)2(OH)4-4H2O]. It has a pale blue to blue color, a white to light blue streak but most important for identification, it usually occurs as prismatic, acicular to bladed, translucent crystals.  Guanacoite is often found as tiny blades lining, or associated with, vugs of arhbarite.  Again, it is a rare mineral only known from the Type Locality, Morocco, and Spain.    The copper zinc carbonate, rosasite (R) and the arsenate mixite (M) from the Tintic district..  FOV ~ 1 cm. Photo: Mike Nelson.

SUPERMOONS, CREDNERITE, AND BLACK COFFEE

 

My posts this summer/fall have been non-existent as I noted in my last and only post.  I finally have conquered my office, sort of, and now the garage awaits me---a never ending task. One can never “catch up” with organizing the garage, at least not me ( and virtually all my friends). Unfortunately, that mighty office conquer has not left much time for minerals except for a few days this week. I am now, and have in the past, been paying for the sins of my youth, along with most of my male friends, as we all make numerous visits to the dermatologist. No hat wearing while riding a tractor in the hot Kansas summer sun. So, this current surgery involved removing carcinoma lesions from my scalp, and the side of the nose. Not much fun after the injected numbness wore off as each demanded 5 or 6 sutures. Of course, “today’s hurt” is much better than the alternative!

But there are joys in life as this last month has been exciting for ole dedicated moon watchers like me. The home we purchased here in the Village of Holmen, WI, has tall red pines and a deciduous understory as the eastern property border. The western part of the neighborhood  also has trees that block a view of the horizon. However, in the “middle” there is a huge expanse of “sky” that is visible. In the mornings I plop my rear on a deck chair, sip my hot, bold, black Kona coffee and watch the sun filter through the pines at sunrise. The birds seem happy, although not noisy as in the spring, but certainly they visit the large feeder. In the evenings I switch sitting areas and hit the rocking chair facing west with a cold IPA at sunset. A nice relaxing beginning and end of the daylight.  BTW, daylight seems to be rapidly disappearing as we slide toward the Winter Solstice.

Observing the night sky is the time to contemplate and celebrate being alive. We have little light pollution here and the noise pollution is very low except for occasional Friday night football games. Last September 17^th I enjoyed the night of the Harvest Full Moon, a Supermoon. And, to add visual joy to the experience, there was a partial lunar eclipse starting at about 7:40 pm CDT and peaking two hours later. Only about 8-10 percent of the upper moon was covered at the peak eclipse but still, that was impressive . The Harvest Full Moon received its name from the fact that before massive mechanization farmers could stay in the fields long after dark. I certainly remember working late in the evenings picking corn in the moonlight for my Uncle farmer. It was money for a poor kid but I must confess I always was on the lookout for wolves and other giant critters!

On October 17^th 2024, the largest Supermoon of the year popped up as the Hunter Moon. The name seems to reference the beginning of the hunting season in olden times when wild game played a major part in the food chain of rural folks. Of course, the moon  appeared “almost full” on a couple of nights before and after the 17th, and I enjoyed watching it move over the trees into my open sky. Several recent nights around the 17^th brought honking geese moving south to better feeding grounds, perhaps due to a little cold snap of 27 F. It seems I don’t need much activity to give me satisfaction; so, the moon cycles and the colorful turning trees make for a “good time” that I intersperse with observations of my minerals. 

Fortunately, discovering “new” minerals in my drawers is always exciting. Recently I pulled open a magic drawer and discovered the cache of perky boxes I snagged last winter in Tucson. The cache of about 30 micros contained mostly rather common minerals but it is hard to complain about the price—ten bucks for the quart bag. I have not examined each specimen but have noted the identifications and collecting localities are attached to all. Unfortunately, the collectors, according to hand printed labels, are varied and unknown.

But common or not, a semi rare “jewel” periodically shows up. Today I pulled out crednerite, a copper manganese oxide (CuMnO₂) with a genesis of oxidation of ores of copper and manganese (that seems reasonable!). The Type specimen was found in the Glockensstern Mine in Thuringia, Germany. Although not always a valid/true indicator, the number of photos displayed in MinDat seems to “say something” about the commonness (is that a word) of minerals. Crednerite displays only 22 photos with 20 from Europe, one from Australia, and one from the U.S. So, it seems rare or at least uncommon. The one U.S. photo is from the Maid of Sunshine Mine in the Gleason Turquoise District in Cochise, County, Arizona. However, Anthony and others, in their seminal 1995 edition of Mineralogy of Arizona (I do not own the latest edition) stated crednerite from “Cochise County, Bisbee, Warren District, identified from an old specimen in the collections of the University of Arizona (UA 6993), Dallas Shaft (Graeme, 1993)”.

The Gleason-Courtland mines (Turquoise Mines) are not far from Tombstone and a few years ago I drove over to see about exploring some old dumps of former turquoise mines. Not a smart move as the claims are private and permission was turned down in a very plain and informative manner. OK, just an ole rockhound wanting to enjoy some outdoor life of his later years!

The Maid of Sunshine is one of eleven mines usually called the Leadville Group, after a Mining Company. The exposed rocks generally consist of a basal Cambrian sandstone/quartzite covered with a shaley- limestone overlain by  thick Carboniferous limestone. Monzonite intrusions, sills and dikes associated with a larger pluton, cut through the Cambrian units and are responsible for bringing in mineral-laden water. At the Maid of Sunshine Mine a large thrust fault shoved the Cambrian Bolsa Quartzite over the much younger Carboniferous Abrigo Limestone. The copper minerals at the mine generally were deposited along the fault plane. Several hundred to several thousand tons (estimates) of copper ore were extracted from the Leadville Group Mines, mostly in the early 20^th Century, and transported by rail to a smelter in El Paso. This mining history noted above was taken from a report authored by S.W. Greenidge in 1917 and reprinted as a digitized file in the Arizona Department of Mines and Mineral Resources Mining Collection located at:   

http://docs.azgs.az.gov/OnlineAccessMineFiles/M-R/MaidOfSunshineCochiseT19SR25ESec16.pdf

 MinDat lists 31 known minerals from the Maid of Sunshine with the photos dominated by blue, green, and blue-green minerals such as azurite, malachite,  and cyanotrichite. One small specimen provided a photograph of crednerite, a steel gray to black mineral with a metallic luster and a hardness o ~4.0 (Mohs). Although the specimen seems to consist of stacked platy crystals. At any rate, my specimen is so tiny that I simply can’t determine the crystal morphology. 

Mass of crednerite crystal in a multimineral matrix. Width of largest mass is ~1.4 mm. Check out the crednerite photo at the Maid of Sunshine gallery.
 

Two different rotated views of steel gray crednerite ??crystals with the upper photo showing a “group” of spheroids.  Width FOV .7 mm.

Unknown mineral in the crednerite matrix. Width FOV ~.5 mm. I could use some help on this one. I presume some sort of crystalline quartz.