PETRIFIED WOOD: WHAT ARE THE STRUCTURES?

UPPER (TOP) OF A PARTIAL LOG REPLACED BY MICROCRYSTALLINE QUARTZ (PETRIFIED WOOD) WITH VARIOUS INTRUDING STRUCTURES.  ARE THESE TUBES PRIMARY OR SECONDARY?  

 In a blog on August 11, I reported on the existence of a quite large piece of mammillary chalcedony observed during a trip to South Park Basin, Colorado.  The blog also contained information about the geology/formation of the Park so that will not be repeated here.

The northern part of the Park (north of US 24) has numerous mountain ranges in the east such as the Kenosha and Tarryall Mountains where the bed rock is generally Precambrian in age.  On the western flank rocks of Paleozoic age front the Mosquito Range.  South of the highway the landforms are more subdued and a wide variety of Cenozoic, volcanic-related rocks overlie Mesozoic bedrock; however, the Mesozoic rocks often crop out in north northwest trending ridges (easily seen near Hartsel and extending north) (Scarbrough, 2001 ).  My interest, in various collecting trips to South Park, has generally been in the southwestern part of the Basin where Scarbrough (2001) has outlined the Cenozoic history as follows:

Deposition of Denver (South Park?) Formation concurrent with Laramide tectonism (compressional mountain and basin building) in the early Tertiary.

Middle Tertiary erosion, then deposition of lake beds, volcanism in the form of lavas and extensive airfall deposits, igneous intrusions, and fluvial deposits.

Pleistocene glaciation in the adjacent mountains producing outwash deposits.

Deposition associated with Holocene fluvial systems.

One of the best-known volcanic-associated units is a formation usually mapped as the Florissant Lake Beds. These beds crop out near Lake George and represent deposition is a basin partially occupied by a late Oligocene Lake.  Thousands of fossil plants and insects (and various other vertebrates and invertebrates) have been extracted from these beds and have produced a wonderful snapshot of life during this time period.  Today, Florissant Fossil Beds National Monument preserves several of the outcrops.

Heading south from Hartsel on CO 9 and 53 Rd, the Antero Formation of Oligocene age (probably equivalent to Florissant Lake Beds) crops out.  However, good exposures are somewhat rare since the rocks are highly weathered at the surface; the landscape is a gently rolling surface.  But, a little prospecting and walking will likely produce specimens of petrified wood.  In fact, I was able to even locate wood in ditches along a gravel road.  However, a word of caution---the land ownership situation in South Park is a jumble of Colorado State land, BLM land, and private land.  In fact, a representative from a federal agency told me that the only way for a novice (like me) to determine land ownership was to take my GPS, get a latitude and longitude reading, and compare such with a federal data base.  An easier way is probably to visit with the ranchers and request permission to prospect.

The Antero Formation is a clastic and volcaniclastic unit that contains water-laid ash, air-fall tuff, siltstone, sandstone, and algal limestone and …contains fossil plants, insects, mollusks, and vertebrates (Epis and others, 1979; Scarbrough, 2001).   A number of writers have noted the presence of petrified wood in South Park, perhaps beginning with Orvando Hollister in 1867:  This Park has salt springs, beds of gypsum, coal shales, veins of chalcedony, carnelian, and other curious stones and minerals.  It has not been thoroughly explored and no one fully knows its resources or curiosities.  Silicified wood abounds in its lower portion, and at one point, about 30 miles west of Pike’s Peak, there is a small patch of petrified stumps still standing, one of which is fifteen feet in diameter [now Florissant Fossil Beds National Monument].

Although I saw much wood in the area, one particular partial log really attracted my attention, mainly for its seemingly internal structures—as seen on the photo.  I don’t know what these structures represent but could guess they might be some sort of activities related to insects.  I am hoping that someone in cyber world will notice these structures and help me out! 

A more detailed account of South Park geology, and the petrified wood and chalcedony, will appear in the CSMS Pick & Pack (probably September) 

REFERENCES CITED

Epis, R.C., Wobus, R.A., and Scott, G.R., 1979, Geologic Map of the Guffey Quadrangle: U.S. Geological Survey Miscellaneous Investigations Map I-1180.

Hollister, O. J., 1867, The Mines of Colorado: Samuel Bowles & Company, Springfield, MA. reprinted 1974, Promontory Press, New York.

Scarbrough, Jr., L. A., geology and Mineral Resources of Park County, Colorado: Colorado Geological Survey Resource Series 40.

Wallace, C. A., J. A. Cappa and A.D. Lawson, 1999, Geologic Map of the Gribbles Park Quadrangle, Park and Fremont Counties, Colorado:  Colorado Geological Survey Open-File Report 99-3 (with map).

GOETHITE, GOETHE, AND KANINCHEN

Know thyself? If I knew myself, I'd run away.

                                                                                  Goethe

I have always been fascinated by the specimens of goethite collected from rocks of the Pikes Peak Batholith.  I knew the mineral was an iron oxide --Fe⁺³O(OH) --and usually some sort of a secondary mineral (in the sedimentary rocks I was used to seeing) but that was about the extent of my knowledge.  Before arriving in Colorado Springs I had always assumed goethite was what I studied in mineralogy class- an ugly sort of “rust”, an iron mineral without much going for it, or some botryoidal lumps.   As students, we used to assume that much of the iron/rust found in the Dakota Formation in central Kansas was goethite and called it bog iron.  Therefore, I was greatly surprised when long time CSMS member Ray showed me his collection of goethite crystals—WOW.  His specimens had delicate sprays of black and shiny acicular crystals and were beautiful.  Ray told me that the mineral is associated with the quartz and amazonite crystals in the vugs of the batholith.  In these type of deposits I believe goethite is a primary hydrothermal mineral.  Which got me wondering—where did the iron come from? Was it leached from some of the iron minerals in the granite such as hornblende?  I don’t know the answer so perhaps some mineralogist could give me some help? 

GOETHITE AND QUARTZ FROM PIKES PEAK BATHOLITH.  KEVIN'S  COLLECTION.

GOETHITE SPRAY FROM PIKES PEAK BATHOLITH.  KEVIN'S COLLECTION.

In the sedimentary environment (bogs) goethite is secondary and the result of oxidation of iron carried in circulating solutions.  So the iron comes from where?  Is it a weathering product, oxidation and hydration, of iron-rich detridal grains? Bog iron was one of the first ores mined in colonial North America and was eagerly sought out by settlers moving west across the continent.  Hematite was commonly mixed in and is also considered to be a “bog iron”.

That got me to thinking about limonite and perhaps it was this mineral, rather than goethite, that was in the Dakota.  What I have found out is that limonite, Fe+³O(OH)-nH₂O, is a combination of several “real” minerals---goethite, lepidocrocite, akaganeite, maghemite, hematite, pitticite, and “jarosite group” minerals and the term is used “for unidentified massive hydroxides and oxides of iron, with no visible crystals, and a yellow-brown streak” (www.MinDat.org).  So, I suppose limonite would be a good generic choice for the Dakota iron oxide.

Goethite/limonite also commonly forms pseudomorphs.  One of the more famous localities in the U.S. is at Pelican Point on Utah Lake near Provo.  At this locality pyrite cubes are replaced by goethite.  In doing so, pyrite the iron sulfide (FeS₂), has the sulfur ions replaced by oxygen and hydrogen and the result is a new mineral goethite (FeO(OH)), an iron oxyhydroxide.  The mineral pyrite crystallizes in the cubic crystal system with the actual crystals commonly manifested in cubes, octahedrons, and pyritohedrons.  Goethite is orthorhombic (three mutually perpendicular axes, all of different lengths—far from the cubes of pyrite) and if crystallized, forms acicular needles or flattened plates.  What one observes at Pelican Point are beautiful cubes, originally pyrite, but now goethite.  I collected crystals many decades ago but am now uncertain as to the land status and collecting possibilities. 

GOETHITE AFTER PYRITE.  PELICAN POINT, UTAH.

What I was really interested in when starting this offering was to find out more about the namesake of the mineral-- Johann Wolfgang von Goethe.  I had read parts of Faust in a college lit class and did not find it interesting at all, and sort of forgot about the man.  A few years ago I had the opportunity to spend several weeks in Germany working with some institutions on starting cooperative undergraduate research programs.  I also was enrolled in a “beginning” German language class, and it was a tough one.  I especially was pleased that the class did not involve “tests”!  But, I learned enough to order dunkles Bier (dark beer), Brot and Brotchen  (bread and rolls), Brat or Wurst (sausauge), and Spitzbein (cured pig knuckles).  What more could I ask for?  And, I could understand the train schedules.  In addition, my spouse could understand the language much better than I could---so we traveled all over Germany on the trains and gained weight eating the aforementioned foods and partaking of adult beverages.  The only problem we really had, and it was not much, was early-on in Belgium where I could not quite understand the entire menu, especially Kaninchen.   I tried to question the staff but they were clueless as to an English translation.  Finally one bright young man held up two fingers beside his ears and said “Bugs Bunny”.  The translation of the dinner---rabbit.

While traveling I had always wanted to visit the city of Weimar---for a couple of reasons:  1) it was located in the former East Germany (I was living in Frankfort, formally West Germany); and 2) the constitution for the post-World War I German Reich was drafted here (1919) and the resulting government was informally known as the Weimar Republic.  This stuck out in my mind from a high school history class since the government was a parliamentary representative democracy (although very shaky at times) and was displaced by Adolph Hitler and his Nazis in 1933.

Upon arriving in Weimar I was sort of stunned at the beauty since the city was largely spared from carpet bombing by the Allied Air Force during WWII—why, I don’t know.  The city was full of very old buildings and a tremendous amount of history.  I was able to visit the Town Church St. Peter and Paul (Herder Church) where Martin Luther visited/preached during his numerous visits from 1518-1540; it is an important part of the Protestant Reformation.  The Duchess Anna Amalia Library includes a 1534 Luther Bible.  Here in Colorado Springs we think that 1850 is old; however, this church is 300 years older!

Weimar was also the home of perhaps Germany’s most important classical playwright, historian, and philosopher-- Joseph Christoph Friedrich von Schiller (1759-1805).  Now, somewhere in grade school our class read the story about William Tell (Wilhelm tell), a play penned by Schiller.  In thinking about it, the story was a pleasant little offering about a bad guy vs. the good guy (Tell) who shot an apple off his son’s head.  Moral of the story, good guy wins.  However, I have gone back and looked at a less sanitized version and the story is quite violent (probably unsuitable for our class).  The play does concern the legendary Swiss archer Wilhelm Tell, but the main thesis seems to be the Swiss struggle for independence from the Hapsburg Empire in the 1300’s.  In the end Tell puts an arrow in the heart of the bad guy, “It is William Tell’s work [he said].  Oh Lord have mercy on my soul”.

One of the things that was sort of interesting to me as I toured Schiller Haus was how short Schiller’s bed was.  He was a not a tall person!

During his final years in Wiemar, Schiller was a friend of Johann Wolfgang von Goethe (1749-1832).  Goethe was brilliant and evidently a genius (no IQ tests then); he was a politician, lawyer, diplomat, poet, writer, novelist, and scientist.  In childhood he would memorize long parts of the first five books of Moses (the Jewish Torah), Virgil’s Latin epic poem Aeneid, and Ovid’s poem Metamorphoses.  I have trouble memorizing my name sometimes!

GOETHE CA. 1828 FROM ORIGINAL PAINING BY JOSEPH KARL STIELER.

As I said, I read part of Faust and it turned me off---no more Goethe for me.  But I understand his greatest literary piece may be Wilhelm Meister’s Apprenticeship.  It is, according to some, one of the top ten novels of all time.  I have not had the energy to tackle this one.  As a botanist (self -taught) he wrote the Metamorphosis of Plants, and also maintained a magnificent garden at the Goethe Haus.  I was in awe in the Garden being able to see plants that Goethe may have touched, or at least planted their ancestors.

But, germane to this piece, is that Goethe inherited a love and curiosity about rocks and minerals from his father.  In addition, he inherited his father’s mineral collection, added to it, and studied them.  All-in-all, his collection included nearly 19,000 stones (as they liked to call them) and may have been the largest in Europe during his life.  And, he advised the local government on "mining".  Some, not many, of his minerals are on display in the Goethe Haus while the majority seem tucked away in museum(s).  I always wondered, where in the world did he display/keep these specimens? 

So, the mineral goethite was named for Goethe in 1806 with the type locality at Hollertszug Mine, Rhineland-Palatinate, Germany (www.MinDat.com).   What I don’t know:  1) is Goethe responsible for the mineral's discovery; 2) did he name it for himself (as at least one author stated); 3) if not, who named it?

As a final side note---in reading the German newspaper Der Spiegel I found out that Germany made the final payment on reparations demanded by the Treaty of Versailles that ended World War I---- on October, 3, 2010.  Now, that little tidbit may win a trivia contest sometime!  I didn't know that any country ever paid off their war debts!

If that doesn’t win then what about the word von in both Schiller’s and Goethe’s name?   This term, von, may indicate where a person is from, his or her place of residence.  However, in the case of Schiller and Goethe von is a nobiliary particle (how is that for the word of the day?).  In the case of Schillar and Goethe a “rich” aristocrat "enobled" (second word of the day) them, made them part of the family, and certainly gave them some resources to continue their humanistic activities.  

As for Faust, he was ultimately saved despite his evil deeds because he continued to strive for perfection right up to the end (instead of not doing so and falling into mediocrity).  Perhaps we can learn from that point. (Thanks Heinz).

A man can stand anything except a succession of ordinary days.

Goethe

mike 

UTAH PETRIFIED WOOD AND FLOWER CHILDREN

This is a two part story—one concerning South Dakota in 1967 and the second describing some petrified wood collected from Utah in 1968.  I hope that you will see the relationship!

In summer 1967 I was working in South Dakota for the State Geological Survey and trying to finish up my MS thesis.  My work took me to several sections of the state but at virtually every location my field assistant and I heard the musical anthem of the summer—San Francisco (Be Sure to Wear Flowers in Your Hair).  It was a haunting and peaceful song that sort of stuck in your mind and you wanted to hum along:

If you're going to San Francisco
Be sure to wear some flowers in your hair
If you're going to San Francisco
You're gonna meet some gentle people there

For those who come to San Francisco
Summertime will be a love-in there
In the streets of San Francisco
Gentle people with flowers in their hair

All across the nation such a strange vibration
People in motion
There's a whole generation with a new explanation
People in motion people in motion

It was the ultimate “flower power” song of the generation and sort of chronicled, and invited, gentle people to visit the city during the “Summer of Love”.  Now, in 1967 I was not about to wear flowers in my hair and instead sported a western battered black hat.  But, I was a dreamer and sort of wondered what it was really like in California.  Was it all peaceful and gentle with a perpetual spring?   However, my Midwestern, small-town, strong parental care upbringing did not allow me to “drop out” and join the migration.  I needed to work, I liked my job, and I needed to graduate, etc.  Later in life I did stop at Haight and Ashbury to see if any magic remained.  The only thing I saw-- several “old hippies” getting their picture taken by the street sign so they could return home and lie to their grand children: Yah, I was there for the love-in and saw Janis Joplin belt out a song.  Of course kids, I didn’t run around naked and I didn't inhale!  In 1967 the area was home to music by Jefferson Airplane, the Grateful Dead, and Big Brother and the Holding Company.  The place was rocking to a variety of "hard" music (for those days).  Back in the "hinterlands" the best we could do was crank up the 50,000 watt KOMA 1520 AM out of Oklahoma City--but only after after sunset!  Baby Boomers all over the Plains and Mountain West would head to their cars and run down the 6 volt batteries in short order listening to the latest hits of Rock n Roll.

In fall 1967 I had a “big week” as I graduated from South Dakota, traveled to Kansas, got married, and drove to Utah for more graduate school.  All worldly items were packed in our car—a 1959 Pontiac with a portable roof carrier.  Of course in those days such a car seemed about 50 feet in length (actually only 18) and was powered by a mighty 285 hp engine; the trunk was enormous.

A 1959 PONTIAC SIMILAR TO THE BEAST WE DROVE TO SALT LAKE CITY. NOTE THE SIZE OF THE TRUNK, AND THE "FINS".  WOW. PHOTO COURTESY OF WWW.CARNUT.COM.

 Actually, we were somewhat terrified as Salt Lake City approached—a couple of kids from small towns on the plains going to the “big city” (250k people then).  With less than $250 on hand we found a landlord willing to let up pay rent in two week increments.  But, I wanted to teach in a university and getting that degree was the path to that job.  It all worked out in the end—I graduated, got the university position, stayed in higher ed for 36 years, and am still married to the same wonderful person.  Life is good. 

One of the first places that I explored in Utah, looking for a dissertation project,  was a few miles east of Salt Lake City near an old mining town called Park City (if only I had bought property then).  This back valley (back of the Wasatch Mountains) was filled with early Tertiary “volcanics”, all sorts of wind-blown and water-lain tuffs intermixed with eruptive volcanics derived from the "Park City volcanic field".  In fact, hard-rock mining for metals (associated with the volcanics) commenced in ~1889 and lasted until the 1950’s.  Currently the local population mines the tourists who arrive by the tens of thousands!  

PARK CITY MINING DISTRICT, SILVER KING COALITION MINING COMPANY, CA. LATE 1800'S.  PHOTO COURTESY OF MININGARTIFACTS.HOMESTEAD.COM.

 Near Park City is a road intersection known as Silver Creek Junction, about where the current I-80 intersects with US 40.  Many of the rocks in this area seemed to have been deposited in a wet area or pond or something like that and petrified wood was common.  Much of it was opalized and sort of a yellow to orange color and was quite beautiful.  Today the land is developed and private, and generally collecting is off-limits as owners do not appreciate rock hounds digging holes.  I have one piece of that wood from those early collecting days.

PETRIFIED WOOD COLLECTED FROM SILVER CREEK JUNCTION.  WIDTH ABOUT 10 CM.

 OK, how does this Utah tidbit tie into Scott McKenzie?  In working on my dissertation I needed access to back country roads/trails between Park City and Evanston, Wyoming, and could not afford a jeep or pickup.  So, I purchased a 90 cc Kawasaki dirt bike and off I went.  In 1968 the “migration” to California by drop outs and/or partakers of magic potions was still evident and Utah was on the main road.  On one trip up a small highway to a back valley I came upon a VW bus trailing blue haze out the windows and chugging along, straining the engine.  Now, that Kawasaki was not the fastest bike in the world but it was speedier than the VW!  As I passed them with a wave I could see eleven long-haired friends of Jesus in a chartreuse microbus (as C. W. McCall sang in Convoy) singing along to McKenzie’s song blaring on the radio—they were heading west with a smile on their face and magic weeds in their pocket. 

In fact, the 1960’s always reminded me of Charles Dickens’ description of the French Revolution (from A Tale of Two Cities, 1859): it was the best of times, it was the worst of times, it was the age of wisdom, it was the age of foolishness, it was the epoch of belief, it was the epoch of incredulity, it was the season of Light, it was the season of Darkness, it was the spring of hope, it was the winter of despair, we had everything before us, we had nothing before us, we were all going direct to heaven, we were all going direct the other way.  The 1960’s were tumultuous to say the least and they certainly influenced the country (and the world) for decades to come.  However, they were interesting and I enjoyed my time during that period.  So, today whenever I hear San Francisco (Be Sure to Wear Flowers in Your Hair) on the “oldies station” I get a little nostalgic as it brings back brings back pleasant memories of youth--

Those were the days, my friend
We thought they'd never end We'd sing and dance forever and a day
We'd live the life we choose
We'd fight and never lose
For we were young and sure to have our way

                                                             sang by Mary Hopkins, 1968

  And, I begin to dream: would that bike have made it to San Francisco?

Rest in Peace Scott McKenzie (1939-August 2012). 

mike

STUMBLING UPON A FAIRBURN AGATE

FAIRBURN AGATE, 2012.  WIDTH IS ~5 CM.

I get sort of euphoric when stumbling upon an agate in the field (here defining an agate as included or banded chalcedony)!  I don’t really prioritize agates in my collection; however, I do have several different specimens representing a variety of “types”.  Of course, my favorites are the Fairburns, the official state gemstone of South Dakota.  Perhaps my fondness is due to a Fairburn ending up as the first “really good” agate that I collected---way back in the 1960’s.  Perhaps it is due to my allegiance to the state of South Dakota where I once picked up a university degree.  Perhaps it is because they are beautiful specimens and quite colorful!  Whatever the case, I like Fairburns (and Teepee Canyons; see my previous blogs on August 18 and June 17, 2012).  Both postings delve into great detail about collecting sites so will not be repeated here.

At any rate, I was back on the Fairburn beds in summer 2012 and for the second year in a row was successful!  Finding a Fairburn of any sort is becoming a nice accomplishment these days so I am quite pleased with my specimen.  It is not the nicest in the state, nor would it make the agate collecting books.  But, it is mine and that makes me happy!

mike

POLYMORPHS: ANATASE AND BROOKITE

Last Saturday I took the opportunity to attend a local estate auction where the handbill advertised thousands of rock, mineral and fossil specimens.  I thought---sure, “thousands”, no way and they are probably junk.  What a pleasant surprise was in store as there were “thousands” of specimens and while some were junque, many more were very nice and collectable.  Most of the fossils were local Cretaceous baculites and really not collectable.  There were also flats of pretty unspectacular microcrystalline quartz available and some went for quite a few bucks!  Why?  But then there were nice collectable individual specimens thrown into flats (beer cases) with about two thirds carrying correct labels.  Some of the flats contained specimens from a single locality such as unlabeled topaz-bearing rhyolite from western Utah.  Most other flats were mixed with perhaps the most interesting being opal (looked Australian) with barite (almost certainly Hartsel, CO).  I guess the packer saw that both were “shiny”. 

I had a great time visiting with, and bidding against (although very hard), about 9-10 other members of CSMS.  I would guess that the ten of us purchased the great majority of the collectable specimens.  The auctioneer would start out with a flat and request bids for any single specimen or two and then sell the remainder of the flat at a single price.  I thought that some of my buys were “quite good”!

One partial flat that I purchased had a small crystal of anatase, something that was not in my collection and a mineral not all that familiar to me ---but I wanted it.  So for $5 I was able to “get it” along with a beautiful, water-clear, double terminated, scepter quartz crystal, a piece of rhodochrosite (with crystals), a nice terminated apatite crystal, some gemmy-green, titanite (sphene) crystals, and several other specimens.  A great buy.

Driving home I kept probing the back recesses of my mind—what do I know about anatase?  Where had I seen specimen(s)?  Then something popped out, or turned on, and I remembered by blog about the mineral brookite (March 7, 2012).  There must be some relationship!  So, in examining the posting I noted my words, and there it was—anatase:  Brookite is a titanium dioxide, TiO_2, crystallizing in the orthorhombic system.  MinDat notes that brookite is one of five titanium dioxide minerals (rutile, anatase, akaogiite, unnamed) that occur in nature---all belong to different crystal systems!  So, anatase is a polymorph of brookite!

Anatase is in the Tetragonal System while brookite is orthorhombic; both are usually found in primary sources as single crystals.  I say primary since all of the polymorphs are not rare in concentrations of heavy minerals from sedimentary rocks.  Anatase has a hardness of about 5.5-6, an adamantine to metallic luster, and a dark steel blue to black color.  The source for the larger crystals seems to be secondary and derived, via hydrothermal solutions, from titanium-bearing minerals in igneous and metamorphic rocks (www.MinDat.org)

 

The specimen now in my collection has a label indicating that Minas Gerais, Brazil was the place of origin.  All-in-all, it was an exciting day.  Now, off to finding shelf space!

 

Anatase crystal from Brazil partially covered with a “clay mineral”.  Width at junction of crystal and clay is ~5 mm.

Brookite crystal from Arkansas.  Length is ~1.75 cm.

ADDENDUM, 5 June, 2103.  Partial large crystal of anatase from Cuiaba District, Minas Gerais, Brazil.  Length ~2.0 cm.