Wednesday, March 13, 2013

GILSONITE, A COLLECTABLE HYDROCARBON



GILSONITE VEIN NEAR BONANZA, UTAH 


One of the major subdivisions of the northern Colorado Plateaus is the Uinta Basin, a large basin associated with the Sevier/Laramide (Cretaceous & early Tertiary) Orogeny and located in eastern Utah south of the Uinta Mountains.  The Basin is a structural basin, as opposed to a topographic basin, meaning that it is a very large syncline, and a compliment to the anticlinal Uinta Mountains.  The structure is related to the Piceance Basin of northwestern Colorado, and the Fossil and Green River Basins north of the Mountains in Wyoming.  The rocks in the Basin are an interesting sequence of latest Paleocene (~58 my) to early Oligocene (~28my) basin-fill sediments consisting of, in ascending order, the Colton Formation (stream and flood plain deposits), the Green River Formation (Lake Uinta, part of a large fresh water lake system), the Uinta Formation (lake edge and lake filling sediments), and the Duchesne River Formation (stream and flood plain sediments on top of the lake sediments.

The Basin is well-known for its production of oil and gas, as well as for interesting examples of solid hydrocarbons--kerogen-rich mudstone (oil shale) and bitumen-impregnated sandstone (tar sands).  But perhaps the most interesting hydrocarbon in the Basin is one that a few years ago (pre-1995) would not be classified as a ”mineral” and that is Uintaite, referred to in this article as the trade name Gilsonite.  In 1995 the International Mineralogical Association adopted a new definition of a mineral as “an element or chemical compound that is normally crystalline and that has been formed as a result of geological processes” (Nickel, 1995).  This definition opened the way for an organic class of substances that included hydrocarbons of which Gilsonite is a member.  Gilsonite is a solid hydrocarbon that comes from the solidification of petroleum.  It is usually a dull black in the field and resembles coal; however, some fresh surfaces are quite shiny with a conchoidal fracture and superficially looks a little like obsidian.
"FRESH" GILSONITE.  PHOTO AUTHOR UNKNOWN.
Gilsonite in the Uinta Basin occurs in long veins (measured in miles) from a few inches to several feet thick and hundreds of feet in a vertical direction.  Most thick veins occur in the Green River and Uinta Formations, both units are Eocene in age.  In fact, the veins seem “rooted” in the oil shales of the Green River Formation.  Tripp (2004) believes the Gilsonite had its beginning in the large amounts of organic debris that accumulated in the sediments of tropical Lake Uinta.  The burial of these sediments created heat and pressure and the Green River oil shales were formed.  Again, burial of the oil shales created water and hydrogen and this explosive mixture was expelled and created fractures in the surrounding rock.  These fractures were later filled with petroleum whose viscosity disappeared with desiccation.  Gilsonite is essentially solid “oil”.
ABANDONED GILSONITE PROCESSING PLANT.
ABANDONED ELEVATOR IN GILSONITE VEIN
Gilsonite was “discovered” by Caucasian settlers in the 1860’s although most did not know of a good use for the substance as it melted and ran from the stoves when used as a substitute for coal.  In the 1880’s a Mr. Samuel Gilson begin to market (as St. Louis Gilsonite Company) “asphaltum” as a waterproof substance and as an electrical insulator.  However, two major problems arose: 1) many of the thick veins of Gilsonite were on the Uintah-Ouray Indian Reservations; and 2) a railroad did not extend into the Uinta Basin and Vernal (and even today the Basin is without rail transportation).  Gilsonite and Uinta Basin boosters took care of the first problem as the U. S. Congress simply took away 7000 acres from the Native Americans (Burton, 1996)!  By around 1900 the Gilson Asphaltum Company (now called the American Gilsonite Company) was the major player in Gilsonite and had consolidated several claims; however, “trucking” (used freely since horsing may be a better term as horse-drawn wagons were used) the Gilsonite 80-100 miles to a Utah rail head was not a very viable option.  So, as with so many projects, “necessity is the mother of invention” (att. To T. Veblen).  The necessity was transportation and the “invention” was the Uintah Railway--started in 1903 and completed in 1911.  The Uinta Basin terminal was at Rainbow near the mines while the southern terminal was at Mack, 22 miles west of Grand Junction, CO, on the Rio Grande Western Railway.  In between those two points was a three foot wide track (narrow gauge) traversing Baxter Pass (8473 feet) and approximately 63 miles of crookedness, curves and grade. The first 28 miles, coming from the south, had 36 bridges while at some of the steepest grades the brakeman could walk faster than the train.  On a few curves the engineer could shake hands with people in the caboose, or so it was said (The Uintah Railway, no date).

The Uintah also hauled passengers, freight, mail and livestock but was abandoned in 1939.  Perhaps its best known cargo---the Dinosaur bones Earl Douglas quarried from what is now Dinosaur National Monument but were then shipped to the Carnegie Museum in Pittsburg.  Today a few grades remain and I have done some hiking along the railway route.  In the 1970’s spikes associated with the tracks were common; today, rare. 

TIMBERS SHORING UP OLD GILSONITE VEIN
After abandonment of the railway, Gilsonite was shipped by truck from a new processing plant near Bonanza, UT.  In the 1950’s a slurry pipeline was built from Bonanza to near Mack, CO, and gasoline was distilled from the mineral until the 1970’s.  Today, American Gilsonite Company continues to mine away in the Basin and sells its product for use in “160 products, primarily in dark-colored printing inks and paints, oil well drilling muds and cements, asphalt modifiers, foundry sands additives and a wide variety of chemical products” (American Gilsonite Company at www.americangilsonite.com).  If visitors travel to the Basin on U. S. Highway 40 it is a very worthwhile trip to make the detour to Bonanza and the abandoned mines.  The deposit is unique and the mines and abandoned facilities are “ghost-like”. 

And, for a special treat, check out the video of the railroad at:
http://www.youtube.com/watch?v=x7IkujWEpm8

REFERENCES CITED
Burton, D. K. 1996, A History of Uintah County: Scratching the Surface in Utah Centennial County History Series: Salt Lake City: Utah State Historical Society, Salt Lake City. 

Nickel, E. H., 1995, The Definition of a Mineral: The Canadian Mineralogist, v. 33, no. 3.
 
The Uintah Railway, 2009: http://home.bresnan.net/~bpratt15/

Tripp, B. T., 2004, Gilsonite, an Unusual Utah Resource: Utah Geological Survey Notes, v. 36, no. 3.




Tuesday, March 5, 2013

VALENCIANITE: ADULARIA (K-FELDSPAR)

ADULARIA VARIETY VALENCIANITE,   LENGTH 7.5 CM.


The other day I had an opportunity to attend a small rock and mineral show.  Actually it was not really a show, as I had assumed from the advertisement, but simply about 15 dealers displaying wares on a number of tables.  Whatever, I am always game for looking at new specimens.

One particular dealer caught my eye since it appeared that he had purchased, at various times, the stock of several different dealers or individuals.  Many of the tags appeared quite old, and some were handwritten in ink---great place to see something interesting!  I was not disappointed and purchased a couple of specimens.

One specimen that caught my eye was labeled Calcite, Valencianite, Valenciana Mine, Guanajuato State, MEXICO. Now, I didn’t have the slightest idea what valencianite was but presumed the mineral had something to do with the small yellow-gold “spots” on the specimen.  Meanwhile, I could see the massive calcite on the “bottom” of the specimen but was uncertain about the major mass of crystals making up the specimen.  It actually looked like feldspar.  At any rate, my interest was piqued and a purchased price was negotiated.  It always seems nice to have a mineral from the “type locality”.  See Zunyite posting on Feb. 21, 2013.

Upon returning to my references I was amazed to learn that valencianite is actually a variety of adularia, which in turn is a type of orthoclase (potassium or K-feldspar) which belongs to the large group known as feldspars.  Wow, this was going to get interesting.  About the only type of adularia that I knew about was the transparent and somewhat opalescent moonstone that is popular ---or so I thought.  MinDat.org states that although some moonstone may be a K-Feldspar the real moonstone (my term) is a variety of microcline.  Now, Gemdat.org notes that moonstone is composed of thin layers of orthoclase (K-feldspar) and albite plagioclase feldspar).  
  
It is no wonder that I get confused, and that our hobby is so interesting and enticing!  Now, as I understand the K-feldspar mineralogy, and that sometimes is a stretch, microcline (triclinic) is a low temperature version (polymorph) of potassium feldspar mostly found in pegmatites while sanidine (triclinic) is a high temperature version common in volcanic rocks, especially things like obsidian and rhyolite.  Adularia (monoclinic) is also a low temperature polymorph from volcanics, especially in hydrothermally altered rocks. But, MinDat.org also states adularia may be partially disordered microcline (see moonstone above)!  Orthoclase is also a low temperature polymorph common in granites and pegmatites but is in the monoclinic crystal system.  If this isn’t confusing enough there is always the many solid solution series in the group; the feldspars are complex and volumes have been written.

So anyway, back to adularia.  It seems as though the variety valencianite was first described at the Valencianite Mine in Mexico and seems to be the major location for collecting the varietal mineral.  MinDat.org lists a location in Calaveras County, California, from seemingly old references, and another from Owyhee County, Idaho.  Neither of these latter localities provided photographs.  The specimens from Mexico, both in MinDat.org photos and from my acquired piece, are not transparent like the gem adularia but do have that opalescent sheen usually termed adularescence.

OK, so now I have a nice specimen of a varietal adularia called-valencianite (KAlSi3O8) but what about the little yellow-gold spots?  That is a tough question to answer.  I am sort of convinced, at least halfway, they may be a fairly rare mineral called milarite (K2Ca4Al2Be4Si24O600-H2O).  I say that only because my back pocket microprobe is not working, and that tiny yellow-gold crystals appear in MinDat.org photos from the mine.  There are other of the spots that appear composed of tiny translucent clusters of cubes but they could be some sort of twined crystals.  To top it off, several of these tiny spots have “very tiny” cubes present with a metallic luster.  I would like to think these might be acanthite (Ag2S) since this is a silver and gold mine.
I am sometimes amazed, but always delighted, to locate a nice specimen at a good price that leads me to more questions than answers.   These sort of dilemmas keep me intellectually alive and like Guy Noir I am one man…trying to find the answers to life's persistent questions.


COULD THESE METALLIC CRYSTALS BE ACANTHITE?  WIDTH OF PHOTOMICROGRAPH 2.40 MM.  ARE THE CLEAR CRYSTALS FORMING THE "BALL" CALCITEDOES "IRON" STAIN SOME AREAS?    


     PERHAPS MILARITE IN ABOVE THREE PHOTOS??

Tuesday, February 26, 2013

LOST DUTCHMAN & SUPERSTITIONS



 

Before arriving in Tucson for the annual rock show I usually spend a few days camping around Apache Junction, the easternmost community of metropolitan Phoenix.  I enjoy the area due to the nearby Superstition Mountains.  This range is one of best-known, at least in name, of any mountain range in the U. S.--presumed home of the Lost Dutchman Mine.  Local legends, take your pick, have it that a very rich gold mine exists in the mountains and/or soldiers buried several bags of gold and/or the local Apache Tribe knew the location of a rich gold mine.  Some variations of the story combine all three theories, and even add several other elements.  Perhaps the best known of the many versions involves members of the Perlata Family “discovering” the mine that “belonged” to the Apache Tribe.  These local Native Americans attacked the Perlatas around 1850 and killed all of the family miners.  Gold seekers have been looking for the lost mine almost since that time!  Among the early seekers was a German immigrant named Jacob Walz or Waltz (or several other spelling variations) who became a “dutchman” as people corrupted Deutsche (people of Germany) to Dutch (as in Pennsylvania Dutch).  At any rate, as the story goes, Jacob rediscovered the old mine after befriending some member of the Perlata family only in turn to fall ill.  On, or near his deathbed, Jacob drew a crude map to the mine for a Julia Thomas.  



Another version of the story has been put forth by local, and noted, author Tom Kollenborn in the 14 January 2008 edition of the AJ News (www.ajnews.com): “The old “Dutchman” Jacob Waltz died in Phoenix at the residence of Julia Thomas at about 6 a.m. on Sunday morning, October 25, 1891. The circumstances associated with his death are as follows. Julia Thomas and Rhinehart Petrasch were attending to Waltz during his final hours. Pneumonia and silicosis had complicated his breathing and Waltz was struggling for air early that morning. Thomas and Petrasch were awakened by the sounds of his struggle and knew the end was near. Julia and Rhinehart rushed out to look for a doctor. Why both of them left Waltz’s side in a moment of crisis is not known. As they exited the house, Richard J. Holmes and Gidon Roberts were walking up the street and Julia asked Holmes to look after Waltz until they returned with the doctor. When Thomas and Petrasch returned with a doctor, Waltz was either dead or succumbed shortly thereafter. Holmes immediately explained the situation to Julia Thomas. He said Waltz had given him the materials in a candle box beneath his bed. Holmes gathered up his newly acquired possessions and left the Thomas’ residence. Holmes’ acquisition of Waltz’s candle box outraged Julia Thomas. According to Holmes and Thomas the box contained about forty-eight pounds of high-grade gold ore. It was estimated the gold contained within the candle box was worth about $4,800.

Weavers Needle, a prominent landmark in the Superstition Mountains.  The Needle is not a volcanic neck but an erosional remnant of indurated volcanic tuff.
Julia Thomas accused Holmes of being a thief. Roberts swore Waltz had given the candle box to Holmes. The local courts did not see it Thomas’ way and Holmes ended up with the candle box of gold ore. This created a schism between the Petrasch and the Holmes families and this schism has survived for more than a hundred years among storytellers of the Dutchman’s lost mine.”
All versions point to the next step and that is Ms. Thomas headed to the mountains looking for gold.  She did not succeed but apparently did the next best thing and begin selling lost mine maps!  By some accounts the sale was successful and Ms. Thomas collected a substantial sum of money.   

Evidently none of the map purchasers found much since people still are looking today for the mine/gold and some local shops even have lost mine maps for sale—they seem to be versions of local lore and opinions and none seem autographed by Thomas or Waltz!  In most cases a well known landmark, Weavers Needle, features prominently in the stories and maps.  
As an added intrigue, several deaths seem associated with the many prospectors, including some of violence at the hands of others (or gremlins who guard the gold).  In late 2009 I remember a story in the Denver Post about a local Denver resident who disappeared while hunting for the mine.  More recently the remains of three prospectors who disappeared in 2010 were discovered in January2011.  Whatever the case, thousands of people each year still hunt for the treasure, and over the years several tens of books have been published describing the Lost Dutchman Mine.



West end of the Superstition Mountains as seen from AZ SR 88.  Layers of volcanic tuff comprise the mountain face.

What is probably more interesting, at least to a geologist, concerns the history associated with these mountains.  Although some remnants of Precambrian igneous, metamorphic, and sedimentary rocks are present in the Superstitions, the majority of the rocks exposed in the range are volcanic in nature, including thick layers of welded and non-welded tuff, and rhyolitic lava, spewed from massive supervolcanos.  As each of these large volcanoes sort of blew out their insides they collapsed and calderas formed (www.gemland.com).  There were at least three, perhaps more, of these supervolcanos in the area of the Superstition Mountains; each caldera was around 10-12 miles in width with varying geologic ages:  Superstition Caldera (~25 Ma), Goldfield Caldera (~15 Ma), Tortilla Caldera (~15 Ma).  Today, after extensive erosion, all that remains of these calderas are immense thicknesses of tuff and rhyolite. The entire area has been referred to as the Superstition Cauldron Complex (Sheridan, 1978).  

Other volcanics as young as ~3 Ma are present and the range itself owes it elevation to late Tertiary Basin and Range faulting and uplift.
The easiest place to observe the mountains is from the Apache Trail, highway AZ SR 88, and running from Apache Junction to the Apache Lakes on the dammed up Salt River.  It is a beautiful drive and there are great exposures of the volcanic rocks along the road.  The traveler also is blessed with a fantastic view of the west end of the Superstitions (5057 feet).  At Tortilla Flats, about 13 miles up the road, the pavement ends at  Canyon Lake; however, a good gravel road continues for tens of miles. 

Stacked units of volcanic tuffs and rhyolite, Superstition Mountains.  Photo courtesy of Charles Ferguson and the Arizona Geological Survey.

Map showing location of Superstition calderas.  Sketch courtesy of Gemland.com.
SR 88 is also the approximate boundary between the Superstitions and the Goldfield Mountains to the west.  The rocks in the Goldfields are similar to the Superstitions as they are part the same volcanic environment, the Superstition Cauldron Complex.  It is in the Goldfields that almost all of the gold and silver in the area has been extracted---not in the fabled Superstitions! 
In 1892, a year after the death of Jacob Waltz, four prospectors from Mesa, Arizona, searched the area west and north of the Superstition Mountains. They found the crumbling remains of mine shafts in a very old mining camp believed to have been from activity of the “Old Spanish”.  And, they found gold—in small quartz veins that had experienced hydrothermal activity.  Over the years the many mines and claims (Mammoth, Bull Dog (thought by some to be the Lost Dutchman), Black Queen, Old Wasp, Bluebird, Mammoth 2, Tom Thumb, Golden Hillside, Fair Strike, Copper Crown, Palmer, Treasure Vault, High Flyer, Gold Bond, Lazy Doc, Gold Strike, Iron Horse [Lucky Boy] Queen, Black King, Tom Thumb) yielded about 61,000 ounces of gold and 22,000 ounces of silver (Wilburn, 1987).  Today the “ghost town” of Goldfield, once home to stamp mills and several thousand people, is being reborn as tourist destination.  Some mine dumps seem accessible along SR 88 and I have collected small amounts of blue chalcedony but not much else.

ADDENDUM 5 April, 2014:  Today I was at a used book sale and picked up a copy of Roadside History of Arizona (1987) by the noted historian Marshall Trimble.  I found an interesting paragraph:  Many historians believe the legends behind the mythical Peralta Mine in the Superstition Mountains actually had their origins in Black Canyon (Bradshaw Mountains north of Phoenix on I-17).  A Peralta did have a mining claim in the area, and he was supposed to have sold them to an accomplice of James Addison Reavis, the "Baron of Arizona", providing the basis for Reavis's fictional tale about a Peralta who was heir to a vast land grant in central Arizona.  Storytellers and seekers of lost treasurer later moved Peralta's mine from Black Canyon to the Superstition Mountains.   So, stay tuned and perhaps next year new info will turn up! 

In late 2012 authorities located the remains of the Denver gold seeker noted in above paragraph as disappearing in 2009.

REFERENCES CITED 

Sheridan, M. F., 1978, The Superstition Cauldron Complex in Guidebook to the Geology of Central Arizona: Arizona Bureau of Geology and Mineral Technology, Special Paper 2. 

Wilburn, J. D., 1997, Goldfield Mining District Geology and Ore Deposits: privately printed.