In wandering through my collection of minerals brought home from the 2016 Tucson Show, I came across a specimen of emmonsite. I reached to the back recesses of my mind trying to remember why I purchased such a specimen. Yes, it is a nice green-yellow color and looked interesting under the loupe but then I remembered—I was going to check and see if emmonsite was named for the famous geologist Samuel Franklin Emmons. Well, I finally got around to checking and sure enough emmonsite [Fe2(TeO3)3-2H2O], a fairly rare iron (ferric) tellurite, was named for a well-known geologist that Colorado has sort of claimed as a native son (although he was born in Boston in 1841 and descended from a long line of native Bostonians—lineages arrived in the 1630s), or at least a favorite son.
|S.F. Emmons, ca. 1860s. Photo courtesy of Library of Congress.|
The following information is abstracted and interpreted from Hague (1912) who wrote a “Biographical Memoir” of Emmons published by the National Academy of Sciences. Emmons was one of those “old fashioned” geologists, attending private primary and secondary schools in Boston and finishing up at the Dixwell Latin School. Emmons was educated to become a gentleman of broad culture, refined manners, and to enter Harvard University, which he did at age 17, and graduated in 1861. When I first read “1861” I wondered why he did not enlist in the U.S Army since Harvard furnished a number of students to the anti-slavery movement. Hague (1912) noted that Emmons’ father persuaded him to pursue a professional career, rather than to follow many classmates into military service. To further discourage enlistment (I presume), Emmons was sent by his father, after graduation, to Europe in order to accompany his mother on a health recuperation trip. He seemed to have spent the summer of 1861 climbing mountains and hiking, and presumably taking care of his mother. She sailed back to the States in November while Emmons toured London and ended the year in Paris. In the City of Eternal Light, Emmons spent nine months working under private tutors in order to relearn French and prepare for entrance exams to the prestigious Ecole Imperiale des Mines (School of Mines). Emmons spent two years at the School of Mines and then decided he wanted to get a more practical mining experience (hands-on) so spent the next year (1865) at the Bergakademie (Mountain Academy) at Freiberg, Saxony, Germany (where there were mines at the city limits). After leaving Freiberg, Emmons spent the winter in Italy and finally returned to Boston in June 1866 (probably to the delight of his family since the conflict was over).
As a graduate student at the University of Utah, I fell “in love” with reading about the geological exploration of the American West via the Great Surveys: F.V. Hayden and the United States Geological Survey of the Territories; Clarence King and the Geological Exploration of the Fortieth Parallel; John Wesley Powell and The Exploration of the Colorado River and its Canyons; George M. Wheeler and the many volumes of Explorations and Surveys West of the 100th Meridian. These surveys of the western United States ultimately were reorganized (1879) into the United States Geological Survey.
|A "Great Surveys" volume picked up at a garage sale 50 years ago.|
This was an exciting time to be at the University since the senior instructors were only a couple or three generations removed from the early western geologists and had traversed the wide-open spaces of the west when it was still “wild.” They had been trained as classical geologists (mostly in the eastern U.S.) and tried to impart their thoughts to the students, especially the need for precise field work. Our field trips often were taken to areas touched by Great Surveys. I sort of fell into a trance standing at the entrance to Ladore Canyon on the Green River trying to imagine what John Wesley Powell felt as he guided his small boats into the “great unknown.” Students were greatly impressed with the detective work of Clarence King (including Emmons) and his geologists in debunking the great diamond find in northwestern Colorado and we wondered if a ruby or diamond still were to be found? Alas, no luck.
But back to Emmons (following Hague, 1912). Upon returning to the States Emmons secured a job, at first as an unpaid volunteer, with the King Survey and they sailed for California in May 1867. He later was hired as an assistant geologist and Hague (1912) noted that Emmons “was full of youthful spirits and manly exhilaration over the work before us.” Emmons worked for 10 years with various aspects of the King Survey that perhaps culminated with the publication (890 pages) of descriptive geology. I did not realize (no surprise here) that after leaving the Survey Emmons “engaged actively in cattle ranching, and for some time made his home in Cheyenne, Wyoming.”
In 1879, the U.S. Congress created the Bureau of the Geological Survey (the USGS) and Clarence King was appointed the first director on April 3. On August 4 of that year King appointed Emmons as “Geologist in Charge of the Rocky Mountain Division” and a mandate to devote his first years to “a study of the mineral wealth of the Rocky Mountains.” In 1886, Emmons was the lead author of USGS Monograph XII, Geology and Mining Industry of Leadville, Colorado with Atlas (~779 pages). Hague (1912) noted that it “won for its author an international reputation…probably no single publication of the geological survey has exerted a more beneficial influence and stimulated more discussion.” Professional geologists could ask for little more than an accolade like that.
After Leadville Emmons lead an active geological life with an amazing number of papers on a wide variety of subjects, including: On glaciers in the Rocky Mountains; Notes on gold deposits in Montgomery, County, Maryland; Geology of the Tintic Special District, Utah. In Colorado Emmons is remembered for excellent papers on Colorado ore deposits, Geology of Aspen Mining District, Geology of the Elk Mountains, Geology of Rosita and Silver Cliff and Mines of Custer County, Geology of the Denver Basin, and Geology of the Ten Mile District. I would encourage interested readers to observe his bibliography (Hague, 1912) found at: https://books.google.com/books?id=vZ0aAAAAYAAJ&as_brr=4&pg=PA309#v=onepage&q&f=true. In addition to his publications, Emmons was one of the founding members of the Geological Society of America and served as the President in 1903.
Also of interest to Colorado scientists: (in the history of the Colorado Scientific Society, the oldest scientific society in the Rocky Mountain region at www.coloscisoc.org. On the evening of December 8th, 1882, a number of gentlemen interested in the formation of a scientific association met in the rooms of the United States Geological Survey, in Denver, at the invitation of Mr. Samuel Franklin Emmons.” “Mr. Emmons, in stating the object of the meeting, said that it seemed to him that the time had come for those persons in Colorado who were interested in true science to unite in forming an association or society, whose immediate object would be to facilitate the interchange of scientific observations and ideas, and promote intercourse among the observers themselves. There should be some means of recording and publishing the many interesting and valuable facts which are daily observed in different parts of the State. This could be done through the medium of a society, and the opportunity thus afforded would no doubt act as a stimulus to some to pursue investigations in directions specially open to them.” “An informal discussion ensued in which the advisability of such a step was advocated, and it was agreed to proceed at once to form a permanent organization.” “The following named persons were unanimously chosen as officers for the first year: President—Samuel Franklin Emmons Vice-President—Richard Pearce Secretary—Whitman Cross.”
Although Emmons was not a “Native Coloradoan” his work certainly qualified him as perhaps the most respected geologist in in the state’s history. Emmons was active until his death in 1911. Hague (1912) noted that “he left a noble record of life’s work well performed.”
Among other honors bestowed on Emmons, Colorado designated a 12,401-foot peak near Crested Butte in the West Elk Mountains as Mt. Emmons. Not to be outdone, Utah designated a 13,448-foot peak in the High Uintas Wilderness as Mt. Emmons. Interestingly, the Utah peak is connected by a rugged ridge to the highest peak in Utah, Kings Peak at 13,534 feet. So, even in death Emmons and his long-time friend and colleage, Clarence King, remain connected.
|Mt. Emmons, Colorado, 12,401 feet. Photo courtesy Google Earth.|
|Mt. Emmons, Utah, 13,448 feet. Photo courtesy Google Earth.|
This offering started out about the mineral emmonsite and so it will finish with the same. Emmonsite is one of a few minerals that contain the element tellurium, a silver-white metalloid (possesses properties of both metals and non-metals). Tellurium is an extremely rare element as most rocks contain about 3 parts per billion and is 8 times less abundant than gold (Goldfarb, 2014), and is related to selenium but may be only mildly toxic! Tellurium is rarely found in a native form.
Tellurium can act as a cation with a 4+ oxidation state as in the uncommon mineral tellurite, TeO2, or with a 6+ oxidation state as in jensenite, Cu3TeO6-2H2O The telluride anion with a charge of 2- can combine with gold and silver cations in the minerals calaverite (AuTe2) and sylvanite (AuAgTe4). These telluride minerals form major gold ores at Cripple Creek, Colorado. So, it is confusing when one talks about tellurium, tellurite, and telluride.
Emmonsite [Fe2+++(Te++++O3)3-2H2O; a hydrated iron tellurite, occurs in a wide variety of habits from microscopic druses, to hair-like masses, sprays, compact masses, globs, and small acicular crystals. I could not locate information on larger than microscopic crystals but MinDat lists emmonsite as belonging to the Triclinic System. It has a green to yellow-green color, vitreous to subvitreous to even dull luster, opaque to translucent to transparent diaphaneity, and is reasonably hard at ~5.0 (Mohs). Its characteristic yellow-green color combined with the often branching (coral-like) or fungus-like shape are the best identifying marks. Emmonsite is a secondary mineral found in the oxide zones of hydrothermal tellurium-bearing base minerals. It is often found with native tellurium and the telluride minerals.
|Green, fungal-like habit of emmonsite. Length main "mass" of mineral ~4 mm.|
Hillebrand (1885) gave the type locality of emmonsite as Tombstone, Arizona. As described by Pearl (1941), the discovery of a new mineral which he named emmonsite in honor of Samuel B. Emmons, first president of the Colorado Scientific Society and one of America's outstanding geologists, was told by W. F. Hillebrand at the meeting of the society at the Arapahoe County (now Denver) Court House on June 1, 1885. The mineral had been sent by R. C. Hills from an uncertain locality near Tombstone, Arizona Territory. So, it would seem that Emmons was (may have been) at the Colorado Scientific Society meeting when Hillebrand gave his description of emmonsite.
Hillebrand (1904) also described emmonsite(?) from Colorado and in Bulletin 262 of the USGS (1905) stated a green mineral was collected at the W.P.H. Mine at Cripple Creek that showed a close resemblance to emmonsite he described 20 years ago (the specimen from Tombstone). However, Williams (1980) believed that the mineral described from Tombstone actually was rodalquilarite, a hydrogen iron tellurite chloride. Eckel and others (1997) then believed it would then make sense to declare the mines at Cripple Creek, Colorado, as the type locality for emmonsite. However, I note that MinDat still lists Tombstone as the type locality.
My specimen of emmonsite was collected from the Bambolla Mine (Montezuma Mine) located in Municipio de Moctezuma, Sonora, Mexico. I have been unable to locate much information on the Mine other than in the 1970s, it was a producing gold mine. I assume, that like nearby mines, mineralization was related to hydrothermal activity associated with Tertiary volcanic action. However, the amazing information is that the Mine, and the nearby (half mile away) Bambollita Mine, are the type localities of at least 23 tellurium-bearing minerals! Also, I stumbled upon an article, actually a discussion, of a micro-mineral group (Associazione Micro-mineralogica Italiana). Luckily, the discussion was in English! At any rate, Ciriotti (2010) noted: Oxide-zone tellurium minerals are relatively rare worldwide… 71 known Te-oxide minerals, 68 of which are considered valid species; most are either tellurite (Te4+O3)2- or tellurate (Te6+O6)6- species… over 60% of the species (43 out of 71) were discovered at only four deposits: Moctezuma, Mexico; Tombstone, Arizona; Centennial Eureka Mine, Utah; and Otto Mountain, California. In fact, nearly a third of all Te-O mineral species were discovered in just one deposit: Moctezuma. Many of these species are still found at only one locality today… The four leading occurrences listed above are all oxidized base metal deposits, and not surprisingly, 60% of all Te-O minerals contain Pb and/or Cu. If Zn and Fe are added in, this increases to 84%... And that sort of sums up my limited knowledge about tellurium minerals.
This is one of those postings that started out as a simple discussion of the Colorado Scientific Society and its first president S. F. Emmons. However, it morphed into the fascinating world of tellurium and the resulting minerals. I am still trying to digest some of the information but needed to draw a conclusion line---somewhere! Unfortunately, the length and breadth of the subject may turn off all but the most dedicated readers and for this I apologize. But, just as a dog worries a bone I worry a subject that I don’t really understand. The good thing is that “new learning” is a joy for me and hopefully keeps my brain alive. My philosophy about learning may be summed up by two rather famous individuals:
Anyone who stops learning is old, whether at twenty or eighty. Anyone who keeps learning stays young. Henry Ford
Every time I learn something new it pushes some old stuff out of my brain. Homer Simpson
Ciriotti, M.E., 2010, Oxidation zone tellurium minerals: Associazione Micro-mineralogica Italiana. http://forum.amiminerals.it/viewtopic.php?t=7168.
Eckel,E.B. (and others), 1997, Minerals of Colorado: Denver, Fulcrum Publishing.
Goldfarb, R., 2014, Tellurium—the bright future of solar energy: USGS Fact Sheet 2014-3077.
Hague, A., 1912, Biographical memoir of Samuel Franklin Emmons, 1841-1911: National Academy of Sciences, Biographical Memoirs, v. VII.
Hillebrand, W.F., 1885, Emmonsite, a ferric tellurite: Colorado Scientific Society Proceedings, v. 2, pt. 1.
Hillebrand, W.F., 1904, Emmonsite(?) from a new locality: American Journal of Science, 4th Series, v. 18, no. 108.
Hillebrand, 1905, Two tellurium minerals from Colorado: U.S. geological Survey Bulletin 262.
Pearl, R.M., 1941, Minerals named for Colorado men: Colorado Magazine, v. 18, no. 2.
Williams, S.A., 1980, The Tombstone district, Cochise County, Arizona: Mineralogical Record, v. 11, no. 4.