TRANSCONTINENTAL RAILROAD, LUCIN, AND UTAH MINYULITE: A RARE PHOSPHATE

 

Photo taken at Promontory Summit on May 10, 1869, at the completion of the Transcontinental Railroad.

Credit Deseret News Archives.  The telegrapher sent the following message: D-O-N-E at 12:47 P.M.

I have always been interested in Utah geology since leaving South Dakota and Kansas in 1967 and heading to the University of Utah for three years of grad school.  Since rambling around the state on “field trips” was an important part of the curriculum, I became enamored with the great variety of rocks, minerals, and fossils “out there” for picking.  And picking and digging I did, but mostly for fossils.  I also found that after leaving the Wasatch Front in any direction the country was pretty wild and sparsely inhabited—perfect for a geologist and nature lover.  Over the years I walked many a mile looking for someone to help extract my vehicle or digging many hours to pile rocks under the wheels in a mud hole.  I learned early to take along plenty of water, lots of food, and extra petrol. But I, and later with my mentored students, saw some fascinating geology and noted the brightness of the stars on clear nights in the desert.

My intense interest in Utah minerals never really started until I took my leave from academe, moved to Colorado Springs, and joined the Colorado Springs Mineralogical Society.  The local mountains brought back sweet memories of hiking in the Wasatch and Uinta Mountains and I started to unpack a few boxes that held Utah “stuff.”  I was surprised at how many Utah minerals I had previously collected and stored away; it was time to sort, curate, collect, purchase, add to the collection, and write.

Darwin didn't walk around the Galapagos and come up with the theory of evolution. He was exploring, collecting, making observations. It wasn't until he got back and went through the samples that he noticed the differences among them and put them in context.        Craig Venter

One of the first specimens I nabbed in my new quest was from a rock/mineral shop in Ogden and was the green gemmy phosphate labeled variscite collected from the “Lucin Locality” in far northwestern Utah. Box Elder County, home of Lucin, is a huge hunk of land stretching from the Wasatch Front at Ogden, north along I-15 to the Idaho state line and west to the Nevada state line.  It also takes in the north half of Great Salt Lake.  The County has 5,745 square miles and outside of the small communities along the interstate is sparsely populated; the county seat Brigham City has a third of the county’s population of 57,000.  Roads are few and far between with UT 30 the only major road. 

Lucin is a well-known term in Utah due to the “Lucin Cutoff.”  The original Transcontinental Railroad ran from Ogden, in the Wasatch Front, west until toward Wendover, Nevada, on the State line but needed to detour north around Great Salt Lake. Old Lucin was a water stop for the railroad and was situated about 10 miles north of its current location.  In 1901 the railroad started construction of a trestle (~12 miles) and a causeway across the Lake and then rerouting the railroad in the general direction of Wendover.  Well, the residents of Old Lucin were about to lose their livelihood so they packed up ”lock, stock, and barrel” and moved south 10 miles to establish a new water stop at New Lucin and hence the Lucin Cutoff was in place.  The Cutoff shaved about 44 miles off the length of the railroad and also eliminated numerous curves needed to cross the Promontory Mountains. By 1959 the Central Pacific Railroad eliminated the need for a trestle and completed a causeway across the entire Lake.

In addition to the railroad, mines in the Lucin District produced, from 1870-1955, about three million dollars (year of value unknown) of low-grade copper and iron from over 6000 mines, pits, badger holes, and other miscellaneous diggings (Blue, 1960).  New Lucin is a deserted and a “Ghost Town” today.

The original route of the Transcontinental Railroad and the Lucin Cutoff.  Map Public Domain with author unknown. 

I have tromped around some of Box Elder County looking for vertebrate fossils in Miocene and Pliocene tuffaceous sediments.  I was not terribly successful but did publish on an interesting Tertiary rodent from the more eastern part of the county.  I also had the opportunity to see, in my field tripping days at the University, the Precambrian rocks in the Grouse Creek Range north of Lucin.  In those days the rocks were generally listed as older Precambrian.  Today they have more specific Archean (older) and Proterozoic (younger) ages assigned and are known as an accreted terrane, about the same age as the Wyoming Craton (>2.5 Ga), or even part of that Craton.

Location of Grouse Creek accreted terrane.  Map Public Domain and credited to: Abenne1 / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0)

In addition, a couple of my Postings described minerals collected in the Tecoma Hills near Lucin (see Feb. 12, 2019).  However, the best- known mineral collected from Box Elder, County is the green phosphate variscite (but probably metavariscite).  It is similar looking as the variscite collected by Ed Over and Art Montgomery from the Little Green Monster Mine in Clay Canyon, Oquirrh Mountains west of Salt Lake City.  However, those Clay Canyon concretions are more colorful and contain a greater amount of crandallite (another colorful phosphate).

The Lucin phosphates were first collected and mined in the early 1900s by Frank Edison and Edward Bird on their Utahlite Hill Claim.  Since 1910 there have been a variety of rockhounds and claim owners prospecting on the Hill (mainly for variscite).  Today there is a small open pit that was previously mined but Marty and others (1999) stated “the mineral and surface rights originally belonged to the Union Pacific railroad.  Santa Fe Gold/Newmont recently acquired the mineral rights.  The property is presently under lease…”  I don’t know what has happened in the last few years since the Marty paper.

Of the minerals at Utahlite Hill, one of the more rare and most interesting is minyulite, a hydrated potassium aluminum phosphate [KAl₂(PO₄)₂(OH,F)-4H₂O].  The orthorhombic crystals are prismatic, elongated and usually terminated. Most crystals are colorless although some may exhibit shades of pale white, light green, or yellow. Crystals are tiny, usually a millimeter or two, transparent, soft (~3.5 Mohs), and often form radiating spherules or sprays. The luster ranges from vitreous to silky.

 

White sprays and spheres of silky minyulite needle-like crystals. Width of mineral mass ~2.5 mm top photomicrograph; length of middle mineral mass ~2.5 mm; width of bottom mineral mass ~6 mm.  The matrix is probably a druse of carbonate-fluoroapatite.

Marty and others (1999), in their definitive article on the Utahlite minerals, noted that minyulite crystals were limited to one small pocket and that area is now inaccessible. I have no information on the original collector of my specimen except that at one time it was in the collection of Shannon Minerals in Arizona.  Nikischer (2012) described a substantial accumulation of Lucin minyulites originally collected by Ted Morley (Piedmont Minerals). Nikischer purchased the Morely collection (early 1970s) but did not “locate” (in the several tons of mineral flats/boxes) and describe the minyulite until ~2012.  It seems these Morely Lucin specimens “may actually be the finest minyulites ever found!” However, I could not locate Lucin minyulite listed as “for sale” on the current Excalibur, or Shannon Minerals websites, nor in fact, on any dealer website.

Minyulite is a secondary mineral that needed an original phosphate mineral(s) to form.  At Lucin the secondary phosphates formed from hydrothermal solutions percolating through, and dissolving, ions in the Meade Peak Member of the Permian Phosphoria Formation. The phosphatic limestone and chert of the Phosphoria is highly brecciated and allowed fluids heated by nearby igneous intrusions to roam through the rocks and reach cooler temperatures where crystallization of the secondary phosphates occurred.  Minyulite is probably the last secondary phosphate to crystallize.  (Marty and others, 1999).

With my interest in both phosphates and the Black Hills of South Dakota it would be interesting to nab a minyulite specimen from the Ross Hannibal Mine in the Lead District.  I will keep my eyes peeled.

I want to thank Tom Loomis of Dakota Matrix for creating and encouraging my interest in the phosphate minerals of the Black Hills and other localities.

 

REFERENCES CITED

Blue, D.M., 1960, geology and ore deposits of the Lucin Mining District, Box Elder County, Utah, and Elko County, Nevada: M.S. Thesis, University of Utah.  

Marty, J., D. G. Howard, and H. Barwood, 1999, Minerals of the Utahlite Claim, Lucin, Box Elder County, Utah: Utah Geological Survey Miscellaneous Publication 99-6.

Nikischer, T., 2012, An old discovery of superb minyulite: Mineral News, vol. 28, no.4.

LUCIN UTAH

DUSSERTITE? (BARIUM IRON ARESENATE) FROM THE CARLIN TREND, NEVADA

 

Specimen from Briding Estate Sale 

Most rockhounds probably think of California, Montana, and Alaska when gold is mentioned, most likely due to the available nuggets and small grains on the market.  However, all 49 states added together cannot compete with Nevada in the current production of gold. In fact, according to the US Geological Survey, if Nevada was a country, it would be the world’s fourth-largest gold producer, behind China, Australia, and Russia. In 2018 Nevada produced 5,581,160 troy ounces, representing 78% of U.S. gold and 5.0% of the world's production. Total gold production recorded from Nevada from 1835 to 2017 totaled 205,931,000 troy ounces, worth ~$322.6 billion at 2020 values (George, 2018).  BTW, gold, and other bullion is sold and traded in troy ounces and there is a difference between an ounce of salt and a troy ounce of salt, about 10%: 1 troy ounce = 1.097 ounce.

Gold in Nevada was originally discovered, at least by North Americans of European descent, when California 49ers were heading west in 1850; however, it was small amounts of placer gold and the travelers were more interested in heading to the “bonanzas” in California.  Less than a decade later silver became the main precious metal target and in 1859 the discovery of the Comstock Lode was made public, the rush was on, and silver became “king.”   But, as with most precious metal booms, the mines played out and in 15 years many miners had departed the Mining Camps for supposed “greener pastures.”

Although Nevada has many gold producing areas, by far the major group of mines is located in the Carlin Trend in the north central part of the state, a 15-mile-wide by 40-mile-long belt of gold deposits that has since produced more gold than any other district in the U.S. While estimates vary, the Carlin Trend is believed to contain up to 180 million ounces, making it the second-largest gold resource in the world behind Witwatersrand in South Africa.

The Newmont Mining Corporation is credited with the discovery of gold in the Carlin Trend ~1961-62; however, it was slow going at first due to: 1) the gold in the ore is quite small, <0.1 to 10.0 microns and disseminated throughout the rock; and 2) the price of gold in the 1960s was established at ~$35 oz. At the $35 oz price the cost of mining Carlin Trend gold was not very cost effective.  In the early 1970s when gold became unhinged from the U.S. dollar, the price fluctuated, and generally moved upward. Another trend that made Calin low grade gold profitable was the development of open pit mining and cyanide heap leaching.

The other major player in the Carlin Trend was Barack Gold.  In 2019 Barrick Gold merged its Nevada mining operations with Newmont Gold into a company called Nevada Gold Mines LLC. Barrick Gold owns 61.5 percent of the new entity with Newmont Gold owning the remainder.  Today, Nevada Gold Mines dominate the production of gold in the Carlin Trend. As best I can determine from an investment report is that in 2019 Newmont produced ~2,218,000 and Barack ~1,475,000 troy ounces of gold, and in 2020 Nevada Gold Mines has only slightly lower production projections. That is a lot of gold!

OK.  But I do not have a single gold or silver specimen from Carlin rocks! What I do have is a nice specimen of dussertite, a complex barium iron arsenate [BaFe₃(AsO₄)(AsO₃OH)(OH)₆] collected, according to an older looking label, from the “Gold Quarry Mine, Carlin, Nev.”  According to MinDat dussertite from Elko County, Nevada, is known from the Rain Mine in the Carlin Trend and the non-Carlin Tecoma (lead over on the Utah line) and Wells (tungsten east of Carlin) Districts.  USGS data lists barite and dussertite as gangue minerals in these three mines. The Gold Quarry Mine is one of the largest mines in the Carlin Trend and MinDat lists 111 known minerals collected from the Mine, but no mention of dussertite! In addition, USGS data also does not list dussertite as a gangue mineral. I am not quite certain what all of this means except that MinDat photos of dussertite from the Rain Mine look like my specimen!

Dussertite is an arsenate and as common in that group, is some sort of a shade of green or yellow green or yellow and is an oxidized and alteration product of a primary arsenic mineral, usually arsenopyrite.  In fact, it seems amazing to me how many secondary minerals are produced from the alteration of arsenopyrite!  The crystals of dussertite are tiny, flattened and often hexagonal shaped, and at times the plates are formed into rosettes.  Crystals are semi translucent, soft at ~3.5 (Mohs), and with a vitreous luster. With that said, I remain a little confused with the specimen from Nevada! Evidently, according to MinDat, dussertite may be “aggregated into crusts.”  I have found few photos of a crust of this type, or a least close: 1) MinDat RQE-FR3 from France, Christian Auer; 2) MinDat 595-WUL from the Rain Mine, Carlin Mining District, Elko County, Nevada; 3) two specimens from Dakota Matrix, one from Algeria and one from Rhyolite Prospect, Nevada.  The Carlin specimen I have is a crust compose of numerous, submillimeter, prismatic and acicular yellow to yellow-green crystals—there are no flat tabs.

An aggregate of submillimeter dussertite crystals forming a crust on matrix. 

A cluster of tiny, clear barite crystal.  Width FOV ~4 mm.

A crust of dussertite crystals.  Width FOV ~3 mm. 

Clear barite crystals with dussertite.  Width FOV ~4 mm.

So, in my mind there are two questions: 1) was my specimen collected from the Rain Mine or the Gold Quarry Mine; 2 is the crust “really” dussertite?  Those are some of life’s persistent questions.  I will continue to investigate and maybe even get an answer from Tom up at Dakota Matrix.

REFERENCES CITED

George, M. W., 31 January 2018, Mineral Commodity Summaries 2018: U.S. Geological Survey.

MINERALS OF THE BRIDING ESTATE SALE: PART II

 

As noted in previous postings Rebecca Nohe Estate Sales recently dispersed the rock and mineral collection of longtime Colorado Springs Mineralogical Society Member Laurann Briding.  The sale attracted a large number of buyers wearing masks who were admitted via reservation (due to Covid-19 pandemic).  I was in the second group on Friday and came home with a few interesting specimens.  The narrative that follows is a continuation from Part I and starts with fluorite and calcite from the Illinois-Kentucky Fluorspar  District.

Honey-yellow fluorite, white sharply point crystals of calcite, translucent almost colorless, large calcite crystals, and colorless fluorite at top. Width FOV ~4.7 cm.

Two generations of calcite crystals scattered on the fluorite crystals.  Width FOV ~1.4 cm.

This is an interesting situation.  The larger transparent calcite crystal is covered with a later generation of slender, prismatic, snow-white calcite crystals.  Width FOV ~1.4 cm.

A second generation of clear cubic fluorite crystals.  The top border mater is synthetic material that was glued to, and held the specimen.  Width FOV ~1.4 cm.

 There are a few large, translucent "first generation" calcite crystals.  Width FOV ~ 1.7 cm.

The flat held a nice fluorite with calcite that has a small old-looking label stating it came from Cave-in-Rock, Illinois.  This, of course refers to the famous Illinois-Kentucky Fluorspar Area with the most famous mine being (probably) the Minerva #1.  Most specimens that simply say Hardin County, Illinois, or even just Illinois, are routinely assigned to the Minerva #1 (Ozark-Mahoning No. 1 Mine).  There certainly are rockhounds and mineralogists who can assign the specimens to specific mines; however, that is above my pay grade.  I have several specimens from the Area picked up on a field trip back in the 1960s, but this specimen was included in the flat and actually is pretty attractive.

The fluorite (CaF₂) in the specimen is composed of interlocking washed-out, honey-yellow cubes (with one small purple cube) along with a second generation of much smaller clear cubes.  Scattered around on the cubes are what appears to be three or more generations of calcite crystals.  The largest are clouded, poorly formed, colorless crystals with a matte luster that I first thought were witherite.  However, they effervesced rapidly in dilute HCL and so I called them calcite.  A second generation consists of long, prismatic, sharply terminated, colorless to white crystals some of which are encased, partially or completely, within the fluorite.  There appears to be a later generation of a snow-white, slender long crystals covering these original prismatic crystals.  Finally, there are clusters of very tiny, prismatic, colorless, transparent calcite crystals scattered around.  Quite a selection.

The colors of fluorite in the District vary considerably but perhaps it best known for purples and blues with color caused by various elements substituting for some of the calcium in the chemical composition. The cubic fluorite crystals have perfect cleavage and will produce a nice octahedron.  Tourist stores across the nation sell these cleaved specimens by the thousands.

Although we have fluorite here in Colorado associated with pegmatites, the Illinois-Kentucky District fluorite was deposited in fractures and faults associated with fairly flat lying Mississippian Age limestones (~330 Ma).  Low temperature hydrothermal brines, of later age (~150-250 Ma), then migrated into the voids while also partially dissolving some of the wall rock before depositing the fluorite.  The District seems related to the Mississippi Valley Type mineral deposits that produced the lead-zinc districts of Missouri, Wisconsin, and other states in the Midwest.  The question of the day is did the brines originate locally around hidden igneous intrusions, or did they migrate from the southern U.S. (today’s geography) that was tectonically active due to plate collisions?

The Mexican State of Zacatecas is in the north central part of the country and is known for the tremendous abundance of minerals and especially silver. MineraliA (2011) noted that “today the state produces 60% of the national product of silver, placing it as the second largest producer in the world. The soil is riddled with veins of silver, gold, mercury, iron, zinc, lead, bismuth, antimony, salt, copper, quartz, kaolin, onyx, calcite, cadmium, and wollastonite.

One of the great mining towns in Zacatecas is Concepcion Del Oro. Iron, lead, copper, zinc, silver, and gold have been mined since at least the mid-1500s and the production of silver, gold and copper continue today. The mines around the town are not well known for pyrite; however, a pyrite specimen was in the mixed flat and so it came home with me.  I wanted to check it out since I am not into collecting pyrite due to possible “pyrite disease” and the release of corrosive sulfuric acid and harmful sulfur dioxide gas.

Above three photomicrographs show pyrite replacing pyrrhotite.  The middle and upper photos show crude hexagonal shape of original pyrrhotite.  Width FOV ~1.2 cm.

In examining the specimen under a scope, I decided “something was kooky” with the way the numerous pyrite crystals were displayed.  The 5 x 7 cm. specimen is covered with small, gemmy, terminated quartz crystals with (up to ~6 x 11 mm) projections of interlocking pyrite crystals (actually the crystals look glued together).  It was confusing.  In searching the photo gallery on MinDat (Concepción del Oro Municipality, Zacatecas, Mexico) I did notice an interesting specimen posted by Dan Winder: “Nice pseudomorph showing granular pyrite that has replaced elongated hexagonal crystals (or stacks) of pyrrhotite. The tallest of these is 5 cm in length and looks like a calcite.”  Now these pseudomorphs certainly looked like the original mineral was calcite but what about pyrrhotite?  So off I go to a browser and type in “pyrite after pyrrhotite.”  Bingo, serendipity again. Dan Weinrich has a nice specimen of “Sparkling pyrite replacing previous pseudo-hexagonal crystals of pyrrhotite” collected from Romania, and others from Russia.  Keep looking. Luis Burillo Minerales has a number of specimens of the same; however, they were collected in Kosovo.  When all else fails, try EBAY! For $160 one may purchase a single clump of “Pyrite after Pyrrhotite, Noche Buena Mine, Zacatecas, Mexico.”  That got me closer although the mine is in a different Zacatecas municipality than Concepcion Del Oro; however, it is close. The Mine also happens to be one of the largest silver mines in the world with reserves of about 1 million oz of gold and 32.4 million oz of silver.

Spray of quartz crystals mixed in with pyrite.  Width FOV ~9 mm.

So, an interesting way to solve a small problem of probable interest only to an ole rockhound like me. The replacement of pyrrhotite (Fe_1-xS where x=0-0.125) to pyrite (FeS₂) seems to involve dissolution and then replacement with perhaps an intermediate formation of marcasite thrown in (see Qian and others, 2011) for a more complete explanation.

Pavement of hematite and goethite included quartz crystals.  Width FOV ~7 cm. 

Photomicrograph of a section of above specimen.  Width FOV ~8 mm.

And finally, at least for this round, the flat contained a sparkly group of brown to brownish-red quartz crystals. Closer examination shows the crystals are gemmy, terminated or double terminated, with the color imparted by the iron minerals goethite and/or hematite.  The specimen is not anything that I would pick up on an individual basis but, it was in the flat. The specimen was collected from Indian Mountain, Alabama, a location well known for producing phosphate minerals (see Posting Dec. 8, 2017).  However, close examination did not produce visible phosphates.  MinDat had single photo of included quartz from the locality; otherwise I am shy of information except that an old looking, handwritten label stated it was collected by one Preston Watts.

REFERENCES CITED

Gujie Fang Xia, Joël Brugger, William M. Skinner, Jiafang Bei, Guorong Chen, and Allan Pring, 2011, Replacement of pyrrhotite by pyrite and marcasite under hydrothermal conditions up to 220 °C: An experimental study of reaction textures and mechanisms: American Mineralogist, vol. 96, no. 11-12.

MineraliA, 2011, Minerals of Mexico: Oaxaca, Mexico.

Morgan, Helen, Greg Arehart, Naomi Oreskes and Half Zantop, 2014, Origin of epithermal Ag–Au–Cu–Pb–Zn mineralization in Guanajuato, Mexico: Mineralium Deposita, vol. 49.