Saturday, December 7, 2013

HUERFANO BUTTE, COLORADO: THE ORPHAN



Many travelers heading south/north on I-25 readily observe a "strange” sort of small butte just north of the town of Walsenburg, Colorado.  I suppose that most people just zip on by and neglect to stop and read the roadside history sign.  Not I, as my father stopped at every roadside sign that happened to come along.  This interest in signs was an attempt to teach his kids about local history and sort of complimented his visiting every roadside attraction that advertised rattlesnakes in a cage.  In 1955 my father, mother and I set out on a trip to southern California in the old ford, exploring all sorts of locations along Route 66.  Always the inquisitive person, my father rarely passed up any attraction.  I inherited this curiosity and so rarely pass up a good roadside history sign, or a coffee shop.  Therefore, I have actually stooped and read the sigh explaining Huerfano Butte.

My early interest in the Butte started many, many years ago when as a student I became fascinated with the great geological surveys of the American West---the reports of the Wheeler, King, Hayden and Powell expeditions in the 1800’s.  I poured over the hundreds of pages in the volumes, mentally noting the places that I wanted to visit and observe, especially those reasonably close to my home in Kansas.  In fact, these writings certainly cemented my career objectives of becoming a geologist and working “out west”.  And, at my first chance, I traveled on a field trip to see the Spanish Peaks and observe Huerfano Butte.  I proudly pointed out to my student colleagues that the land form was illustrated in the great survey tome by F. V. Hayden entitled The United States Geological and Geographical Survey of the Territories.  Later in life I became interested in the travels of John Charles Fremont and was pleased to learn that his fifth expedition to the west noted the Butte.  Today, I often travel down Interstate 25, past the Butte, and wonder what it would have been like to travel with Hayden and/or Fremont.  Then reality arrives and wakes me up as I remember the cold and hunger experienced by the groups: At the killing of this horse, nearly all the men were present. They had not tasted food for nearly two days, and were, consequently, ravenous, and thought of nothing else but satisfying the cravings of hunger. As soon as the horse was slaughtered, without exception, every one cut off a piece, and roasted it at the different camp fires (Carvalho, 1856).
 

“The Huerfano Butte, New Mexico Territory, August 19, 1869” (as seen by the Hayden expedition).
Huerfano Butte, termed El Huerfano by the early Spanish explorers and The Orphan by some, is located about six miles north of Walsenburg near Exit 59.  The elevation of the butte is 6043 feet giving a conspicuous relief of about 100 feet.  Although many people refer to the butte as a volcano (the Colorado state sign calls it “volcanic outcrop”) it falls short of that designation.  More than likely it is a hypabyssal plug meaning that the magma cooled before it reached the surface of the earth. 

Penn (1995) has an interesting story for the Butte and described the rocks as a biotite olivine alkali-gabbro cut by two east-west trending dikes, one a biotite monzonite, the second and smaller one a weathered alkali-lamprophyre.   In more common terms, a gabbro is a dark igneous rock that cooled within the surface of the earth and is the coarse grain equivalent of the extrusive igneous rock known as basalt.  The gabbro at Huerfano Butte has significant amounts of the minerals biotite and olivine with the only feldspar being plagioclase rather than an alkali (high in potassium and sodium) form such as microcline or orthoclase.  The two dikes are composed of other intrusive igneous rocks, monzonite, (mostly equal parts of plagioclase and orthoclase) and lamprophyre (a weird sort of rock with high amounts of amphibole and feldspar).  All this boils down to the fact that the Butte has a major body of coarse grained, dark colored igneous rock with a couple of cross-cutting dikes.  All of the rocks cooled below the surface of the earth; therefore, it is not a volcano.
 

Huerfano Butte looking east from near I-25.
The other interesting story presented by Penn concerns the dates of the rocks.   It seems that both the gabbro and the monzonite have radiometric dates of ~25.2 Ma.  Case closed!  But wait a minute.  Since the dates for both the plug and the dike are identical it seems likely that during the emplacement of the dike, the radiometric date for the main gabbro plug was reset and so actually the plug rocks are somewhat older than the dikes (~25.2 Ma)   A nice bit of detective work by Penn (1995).   

The emplacement of  Huerfano Butte, as well as other relatives---the Spanish Peaks, Gardner Butte,  Goemmer Butte, Bandito Cone, and the Spanish Peaks Dike System—may be related to the opening of the Rio Grande Rift System on the west side of the Sangre de Cristo Range.

Another interesting story concerning Huerfano Butte can be traced back to the Fifth Expedition of the West lead by that intrepid explorer John Charles Fremont.  Fremont hired, in August 1853, an American-born Sephardic Jew by the name of Solomon Carvalho to document the travel.  I note his religion only as something of historical interest since he often went hungry rather than eat non-kosher food, or fresh porcupine that he thought looked like pork:     A large porcupine was killed and brought into camp to-day by our Delawares, who placed it on a large fire burning off its quills, leaving a thick hard skin, very like that of a hog. The meat was white, but very fat, it looked very much like pork. My stomach revolted at it, and I sat hungry around our mess, looking at my comrades enjoying it (Carvalho, 1856). 
  
Carvalho was a master daguerreotypist and was charged with creating a “photographic” record of the expedition.  The explorers left Kansas City in September 1853 traveling mostly along the Arkansas River to near Pueblo and thence over the mountains to southern Utah.  Carvalho documented the travel but unfortunately his prints (except for one) were destroyed in a fire in 1881.  Also, Fremont would not allow members of his expedition to compile private diaries, and Fremont himself never wrote up the results (a long story for later).  However, Carvalho not only broke the rules and wrote a diary, he also published a book documenting the expedition (1856).  In addition, later in life Fremont published his memoirs (1887) and included 30 engraved illustrations of Carvelho’s daguerreotypes, including Huerfano Butte. 
 

Huerfano Butte as copied by Fremont (1887) from a daguerreotype by Solomon Navalho.
In Carvalho’s (1857) words, the expedition traveled up the Arkansas River past the ruins of Bent’s Old Fort and he questioned will the progress of civilization ever extend so far in the interior?… After crossing the Huerfano River, we saw the immense pile of granite rock, which rises perpendicularly to the height of four or five hundred feet, from a perfectly level valley. It appeared like a mammoth sugar loaf, (called the Huerfano Butte).  Col. Fremont expressed a desire to have several views of it from different distances…
To make a daguerreotype view, generally occupied from one to two hours, the principal part of that time, however, was spent in packing, and reloading the animals. When we came up to the Butte, Mr. Fuller made barometrical observations at its base, and also ascended to the top to make observations, in order to ascertain its exact height. The calculations have not yet been worked out.
If a railroad is ever built through this valley, I suggest that an equestrian statue of Col. J. C. Fremont, be placed on the summit of the Huerfano Butte; his right hand pointing to California, the land he conquered.

All of these early explorers who came upon and marveled at Huerfano Butte were productive and well-known citizens of the U. S.  One can only wonder about their mindset as they trudged up the river valley and noted the little orphan sticking up out of the plains.

Epilogue
Carvalho became seriously ill and left the Fremont party in Parowan, Utah and then traveled to Salt Lake City. While in Salt Lake, he became a popular portrait artist with subjects including Brigham Young, authorities of The Church of Jesus Christ of Latter Day Saints, and other Utah notables.

In 1857, Carvalho went on a peace mission with Brigham Young to central Utah and provided prints for such Native Americans such as Wakra, Indian Chief.  His daguerreotypes are the basis for book plates, oil paintings, and wood block prints. Carvalho authored Adventures in the Far West (1857), a book containing his reflections on Mormon culture.

 
John Charles Fremont served with distinction in the Mexican-American War and the U. S. Civil War ( attained the rank of Major General), mapped part of the upper Midwest, lead five exploring/surveying expeditions to the American West, served as the Military Governor of California, the U. S. Senator from California, and the Territorial Governor of Arizona.  In addition, he was the first presidential candidate of the newly formed Republican Party (losing to James Buchanan).

F. V. Hayden was a surgeon and Chief Medical Officer of the Army of the Shenandoah in the U. S. Civil War.  He became the geologist-in-charge of the United States Geological and Geographical Survey of the Territories and mapped vast areas of the American West.  Perhaps he is best remembered for using the photographs of Wm. Henry Jackson to help convince Congress to establish Yellowstone as the Nation’s first national park.

American history is not something dead and over.  It is always alive, always growing, always unfinished (John F. Kennedy).




REFERENCES CITED

Carvalho, S. N., 1856. Incidents of Travel and Adventure in the Far West; with Col. Fremont’s Last Expedition across the Rocky Mountains; Including Three Months’ Residence in Utah, and a Perilous Trip Across the Great American Desert to the Pacific. New York: Derby and Jackson.

 

Fremont, J. C., 1887, Memoirs of my Life, 1813-1890.  Together with a Sketch of the Life of Sen. Benton by Jesse Benton Fremont.  Chicago: Bedford Clarke.

Penn, B. S., 1995, What’s the Scoop on Huerfano Butte? [abs.]:  American Geophysical Union Abstracts with Programs.



Sunday, November 24, 2013

"ZINNWALDITE": MICA PIKES PEAK BATHOLITH



Mr. “Rockhounding the Rockies” is a pegmatite digger here in the Pikes Peak area and has collected fine specimens of smoky quartz and amazonite along with some nice fluorite and topaz.  He also has pulled out some really great pieces of petrified wood from the Cretaceous and Tertiary rocks along the Front Range.  The other night he gave me, not one of those beautiful blue-green microclines crystals, but a somewhat nondescript piece of zinwaldite, something that “clutters up” his digging holes in the Precambrian pegmatite.  I accepted it with gratitude since it is one of those strange and weird minerals that so fascinate me.  But wait, zinnwaldite is not really a valid mineral species!

Zinnwaldite from Lake George Ring Complex.  Note brass-colored sheets.  Arrows point to three "faces" of pseudohexagonal crystal.  Maximum width ~ 3cm.
 Zinnwaldite is a lithium-iron mica [KLiFe+2Al(AlSi3O10)(F,OH)2] that is common as euhedral, pseudohexagonal books in miarolitic cavities (pockets) of pegmatites of the Precambrian (~1.05 Ga) Pikes Peak Batholith (Eckel and others, 1997; Foord and Cerny, 1995).  In these cavities the zinnwaldite occurs with the more desirable minerals such as  smoky quartz, topaz and amazonite. It is hard to describe the physical characteristics of zinnwaldite other than to say the “mineral” consists of thin sheets of a brass-colored substance that in side view is a rather non-descript black-brown color.  To me, in a side view, the specimen resembles a fissile black shale.  The sheets of this mice are not as elastic as either muscovite or biotite; however, they may be peeled off and almost appear as a brassy colored shale.  I did notice, however, that other described specimens range in color from brown to green to violet.  The hardness varies from 3-4 (Mohs) and in other localities zinnwaldite sometimes appears as bundles of vitreous sheets forming rosettes.  Zinnwaldite belongs to the Monoclinic crystal system but the individual crystals appear as hexagonal in shape and are termed pseudohexagonal.
 

X-section view of specimen.  Notice layering of sheets.  Width ~3.6 cm.
MinDat.com noted that the International Mineral Association (IMA) has discredited zinnwaldite as a valid mineral and that it is now classified somewhere in the series between siderophyllite (iron rich) and polylithionite (lithium rich) mica.  OK, but what about the Lake George Ring Complex specimens—what are they?  The 1997 Minerals of Colorado (Eckel and others) list them as zinnwaldite.  MinDat.com notes that both siderophyllite and polylithonite are found at Lake George; however, their photos of Lake George specimens are listed as zinnwaldite!  To make it more confusing, at least to me, are the numerous (and definitive) studies by E. E. Foorde and co-authors on Pikes Peak Batholith rocks.  In a 1995 article, Foord noted that the pegmatites contained a number of different micas with the earliest micas (the iron-magnesium micas) forming tapered columnar crystals growing toward, and adjacent to the miarolitic cavity zone which contains the later crystallized micas (the lithium-fluorite micas).  And, that most cavity-grown zinnwaldite crystals show a decrease, from core to rim, in total Fe and Mg, whereas Si, Li and F increase and Mn, Rb, Cs and Na are essentially constant.

So, my question is still not answered.  Is the zinnwaldite collected in rocks of the Lake George Ring Complex classified as siderophyllite or polylithonite?  Or perhaps just put into the “series”, especially since Foord and others (1995) noted that the amount of iron and lithium varied within the same specimen from rim to center! 

I love geology (and life), especially when there are so many questions suddenly appearing out of “nowhere”.  For example, in the middle seat of an airplane—which arm rest is yours?

ADDENDUM 11 June 14:  More "zinnwaldite" from the gut pile of Mr. Rockhounding the Rockies, AKA the resident meteorologist of Lake George.

Pseudohexagonal crystal.
A stack of mica.  Height ~2.6 cm.
Crystal on matrix.  Width of broken crystal ~1.6 cm.
Large broken crystal; stacked micaceous plates.  Width ~7.2 cm.
ADDENDUM 6 MAY 2014:  Mr. Rockhounding the Rockies just presented me with another piece of "zinwaldite."  In his urgent quest for amazonite, he simply tosses some specimens in the "gut pile."
Zinnwaldite from Lake George Ring Complex.  Note pseudohexagonal crystal.  Maximum width ~4.5 cm.

REFERENCES CITED
Eckel, E. B. and others, 1997, Minerals of Colorado: Denver      Museum of Natural History, Denver. 

Foord, E. E., P. ÄŒerný, L. L. Jackson, D. M. Sherman, and R. K. Eby, 1995, Mineralogical and Geochemical Evolution of Micas from Miarolitic Pegmatites of the Anorogenic Pikes Peak Batholith, Colorado:  Mineralogy and Petrology, v. 55, Issue 1-3. Large broken crystal; stacked micaceous plates.  Width ~7.2 cm.