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                           Mineral of the Month--February

                  Petrified Wood

                                       Silicon Dioxide (Predominately)

                              SiO2

                   Petrified Wood, Part I

               By Ken Casey

Preface    

     In the next two episodes of our Mineral-of-the-Month we will be visiting Petrified Wood.  Not just
on the surface, but deep within this ancient wood’s cells.  Part I will cover the chemistry and science
of what makes it, i.e., the process of petrification, it’s geology, and what gives it its array of colors. 
We will see some lapidary examples, as well.  And, we will begin nearest our clubhouse in the United
States to trek our petrified forests.

     In part II, we will go into paleobotany, more lapidary uses, lore and metaphysical applications, and
travel internationally, to see what the rest of the world proudly offers as paleo-beauty from their homes,
as well.

     So, put on your hardhat and safety sunglasses.  We’re off to explore the many preserves of ancient
flora. Let’s go!

    

Introduction

     Good morning!  I hope you are all ready for our excursion into sunny petwood country.  As your guide,
I will suggest places for us to collect, or in the case of special parks and preserves, to just soak in the
multi-hued beauty of stony logs and trunks, to be admired where they fell a long time ago.

     As there are several public and private locations for us to visit on our itinerary, we’ll have to hurry, so
everyone on the club bus, please.  All aboard!

     We’ll travel south from Delaware, then venture across the country westward, until we reach California. 
We can spend the next virtual month scouring the southwest for fossilized plant specimens, while working
on our suntans.  Next month, we’ll endeavor to cross the ocean to sunny Australia, then onto Asia and
other spots on the globe.

IMGP3100.JPG (2842 bytes) Pentoxylon_small.jpg (2151 bytes) aussiejohn.jpg (9566 bytes)
Delaware Petrified Wood
Photo by Ken Casey ©2005
Pentoxylon (Jurrasic), Australia
Photo courtesy of
Dr. Stephen Ervin
Australian "aussie john"
Photo by and courtesy of
Jackie Lapin, SpheresToYou.com  ©2006

    We’ll need a primer on petrified wood.  So, as the wheels on the bus roll us southward, let’s study up
on our current favorite.  We’ll begin with science.

What’s In a Name?

     The word “petrified” comes from the Greek “petra”, meaning rock.  So, wood that has transformed into
rock is “petrified wood”.

 

What is petrified wood?

     By general definition, petrified wood is tree material that has undergone mineralization.  This could
loosely apply to man-made pressure-treated lumber or naturally preserved ancient kauri wood from New
Zealand.  More on that later.

     For our intensive purpose here, we intend to visit nature’s fully fossilized trees.

     Petrified wood is a fossil created by the replacement of a tree’s plant cell shapes with minerals,
such as quartz, calcite, or pyrite.  A stone cast is left after the lignin and cellulose decay.  It’s telltale
colorful grain patterns and concentric rings are fostered by staining minerals, such as iron, manganese,
or copper. 
Pure silica exhibits a bluish-white hue.

     The quartz variety predominates the world’s paleoforests.  On the Moh’s scale of hardness it rates
a 7, equal to quartz.  It is tough, yet brittle, breaking as does cryptocrystalline quartz.  Amazingly, it
can weigh many times that of a piece of similarly sized wood.[i]

 

Color Chart:
az_petrified_wood.jpg (30371 bytes) Petrified Wood comes in all colors of
the rainbow.  The following minerals
give the wood it's characteristic palatte:

http://en.wikipedia.org/wiki/Petrified_wood

(Left) Closeup of Petrified Wood from the Petrified Forest National Park, Arizona
Photo courtesy of Christy Marx, Professional Photographer 
©1997-2006

     There are three main steps towards permineralization of living plant matter: (1.) encapsulation,
or removal from an environment that causes decomposition, (2.) introduction of sufficient quantity
of a mineral-laden solution to bring about chemical-biochemical replacement of cell structure, and
(3.) time.

     At what point during the petrification process (or preservation process) do we determine that
wood is in fact “petrified wood”?  Is a partially or fully done process sufficient for our definition?  Can
it be man-made, or is nature the sole producer?  Or, is age a factor?

     There is a debate over whether certain, recently recovered wood from the ground has actually
undergone the process of petrification.  There are three examples that come to mind.  They are:
New Zealand kauri wood, century-old sunken logs, and flood-covered landscape living tree remnants.

200px-Kauri_Te_Matua_Ngahere.jpg (43466 bytes)

     The first is the southern hemisphere’s millenias old kauri wood.  Recently recovered or “mined” from the peat bog-laden earth, ancient kauri (Agathis australis) is estimated by radio-carbon dating to have been “preserved” in the ground for around 50,000 years.  The only officially-licensed New Zealand “mining” company explains that harvesting is state-monitored, so it is rare and can be expensive.[iii]   

     Partial mineralization has occurred, thus giving this workable wood some superior degree of hardness and a cognac-colored sheen that underscores a beginning to fossilization.  Though not fully petrified, natural longer-scale preservation has increased its beauty and value.  Buried under a peat swamp, after having lived for about 2,000 years, each tree has rested, untouched since the last Ice Age. We can compare the old wood to modern trees, as kauri still graces the New Zealand landscape.

     One can both visit the living members at the Northland Forest Park, and later procure online some ancient lumber from a hardwood vendor, Ancientwood, Ltd. of La Pointe, Wisconsin, for use and study.  If you are keen on paleobotany, this job is for you.  Some folks enjoy working it as wood.

(Left): Agathis australis (Kauri tree) from New Zealand, called 'Te Matua Ngahere' after the Maori 'Father of the Forest' (wikipedia)

    The second is the spoils of latent logjams.  For about 100 years, some cut logs sent downriver
from antique logging transportation operations have sunk to river or lake bottoms, only to have their
harvesting deferred to recent times.  These water-logged bonuses are fully useable in modern
carpentry and woodworking projects.  Whether some mineralization has occurred to harden the
lumber is at issue.

az_petrified_forest.jpg (26682 bytes)      The third is flood-preserved stands of trees.  One recent example are the remains of ancient forests that can be seen poking their highest limbs above the lower water levels of Lake Powell in the awesome Glen Canyon National Recreation Area.  These plants have been submerged by man-made projects for about 40 years.  One could study these.

     Naturally-occurring ancient examples are coastline forests, since sea-levels have risen since times BCE.  An inland example is the shifting of water levels in Yosemite National Park.  Dead stumps stand in testament to volcanic and tectonic processes, perhaps preserved by dissolved volcanic gases or related mineral-bearing waters.

(Left): Looking downslope of an erosion channel at the Petrified Forest National Park
Photo by and courtesy of Christy Marx  ©2006

     As an historic supervolcano in the west spewed an ash cloud into the believed prevailing
paleowinds, deposits reached as far east as Nebraska.   I wonder if the process is occurring right
now under the fallen forest on the slopes of the currently active Mt. St. Helen’s volcano at the
Mt. St. Helen’s National Monument in Washington state.

 

Man-made Analogs

Pressure-treated Lumber

ptpine.jpg (20758 bytes)      Today’s pressure-treated pine wood is just that, lumber infused with chemicals, like chromated
copper arsenic (CCA), under intense pressure.  These minerals act to preserve the wood, thus making it resistant to insect infestation and decay from ground and water contact.  Some lumber manufacturers guarantee their product for up to forty years! 

     Last year, during our club’s Junior Booth Labeling Party in preparation for our March 2005 Show, I found a small piece of P-T pine.  It was used as a base to mount a mineral specimen, I believe.  Determined to label it, I suggested we sell it as “petrified wood”, as it was chemically-preserved wood.   Laughing, we put it back in the box, but didn’t offer it for sale.

(Left): Photo courtesy of FLW Wood   ©2006

     Here is an example of a middleground two-fold process: man-made, then naturally lithified.  A
story reported in Australia’s outback gives proof that planted timber fenceposts have been partially
fossilized in recent history, thus giving credence to a faster than previously believed permineralization
process occurring in nature.  The 1918 flood laid sediment and water conducive towards creating
fossilizing conditions.[iv]

     Experimental chemistry has brought petrification to the forefront of the news.  A man-made
process has brought about a ceramic compound that mimics petrified wood. It is amazing that
with a nearby petrified forest, that scientists in Washington state are creating artificial petrified
wood.  Why, do you ask?

     Benefits include filtering pollutants, acting as catalysts, and sponging up contamination.

     The process involves hardening a softwood, such as pine or poplar, bathing it in acid, then
soaking it in silica solution for days.  After air-drying, it is cooked in an argon-filled furnace to
1,400 degrees Celsius, Many experimental and industrial crystals are grown in an argon
atmosphere.   The replicated petwood consists of a new silicon carbide.[v]

     In the article “Instant Petrified Wood Yields Super Ceramics”, Materials scientists at the
Department of Energy's Pacific Northwest National Laboratory have developed a chemical
process that adds a promising new dimension to the search for advanced catalyst technologies,
as well as to cutting tools, abrasives and coatings.”

     These laboratory versions of petrified wood borrow the best aspects of metal and carbon to
create a superstrong material that can take temperatures up to 1,400 degrees Celsius.  They
create it in days, instead of millions of years
.

     The idea it to build ceramics on “wood templates”.  Silicon, titanium, and argon are used. 
The useable end products are silicon carbide (SiC) and titanium carbide (TiC).[vi]

     The amazing porosity of the material lends itself to use as a catalyst or a filter.  This wood
flours can be infused with metals, creating better cutting tools.  And, all this from a renewable
resource!  What will they think of next?

     So, a modified type of truly petrified wood can be of use beyond its outward structure
and beauty.

 

Another application touts a petrifying effect:

     Both a Popular Science, October 1992 article, and U. S. Patent File #4,612,050, outline an
invention owned by Mr. Hamilton Hicks of Greenwich, Connecticut, which explain a process whereby
fresh wood can be
altered by chemical solutions in the lab to create an analogous petrified wood.[vii]

     His Sodium silicate composition patent file abstract reads: “A mineralized sodium silicate
solution for the application to wood has a composition causing it to penetrate the wood and jell
within the wood so as to give the wood the non-burning characteristics of petrified wood.”[viii]

     Australian scientists of Nanotec Pty. Ltd. have devised a newly marketed product which they
tout repels water and UV rays.  Their “Nanoseal Wood” may be defined as man-made petrified,
but actually
may serve as building material.

     It is a “water based, ultra hydrophobic, colloidal solution with self assembling properties to
form the functional surface structure.
  The repellent effect is done by a combination of molecular
structural surface changes and added on hydrophobic properties.”[ix]

     The topically applied liquid seals out air and moisture, thus halting decay, much like the
encapsulated environment in which petrified wood forms.  One must ask how long will it last,
and are we creating petrified wood over time
?

     As the vast Triassic paleoforest that spanned Texas to Utah consisted of ancient conifers, some comparison can be logically made.  Technology has almost defeated the process of aerobic decay.  Even decades old loblolly pine carpentered building members encased in plaster harden with age.

     The afore-mentioned lab-created woods seem to mimic nature’s processed pieces to a defining degree of form.  So, are these cultured products really comparable to this month’s favorite mineral?

(Right): A 15" round cross-section of Utah petwood
Photo by and courtesy of sticks-in-stones.com ©2006

utah1.jpg (126497 bytes)

     Let’s review by reading a passage written about natural petrification, and see how it compares.

     Sometimes the original cellular structure is obliterated and what remains is simply a cast
of the original log; other times, growth rings, bark, knots, and even cellular structure is
preserved with remarkable fidelity. This later, more detailed preservation is possible because
silica and other inorganic molecules are much smaller than organic molecules; rather than
"molecule for molecule" replacement, the organic molecules are actually coated and surrounded
with silica. Small amounts of impurities add color to the fossilized wood: yellow, brown and red
indicate iron; black and purple take their hue from carbon or manganese.
[x]

     Doesn’t this describe the major technical features of our chemists’ processes above?

     So, what constitutes laboratory petrification as a similar, chemical replacement process to
nature, can thus retain our definition of petrified woo
d.

     In past articles, we have mentioned substitutes for nature’s bounty, especially when
quantities are scarce.  For example, turquoise, diamond, and opal have all been man-made.  
Though having uses beyond the gemstone, why should petrified wood be treated any differently? 

 

Geology

     As stated above, similar conditions around the globe create the environment to petrify wood. 
It seems that all three main geologic processes contribute to the creation of our preserved
paleoforests.   Volcanic lava, ejecta, and silicieous ash (igneous), soil and mud deposition
(sedimentary), and mineral-laden groundwater replacement casting (metamorphic), work in
sequence to bring about our painted landscapes of today.

     Experts differ as to the timeframe of formation.  Some believe that millions of years were
required; whereas, others cite instances of objects, such as modern fenceposts being
fossilized after floods.   Most submit that eons have passed before natural examples were
completely mineralized.

   One of the most studied areas is the Petrified Forest National Park in Arizona.  Stratigraphers in one paper state that, two layers of the Upper Triassic Chinle Group contain the bulk of petwood in the park.  Also, the Sonsela Member of the Petrified Forest Formation holds the more brightly colored logs for which the park is known.

     These scientists, Andrew B. Heckert and Spencer G. Lucas, conclude their age-dating as [a]vailable biochronological evidence, including tetrapods, megafossil plants, pollen, and calcareous microfossils, indicates that both the Sonsela Member and the Black Forest Bed are of early- to mid-Norian (220-215 Ma) age.[xi]

     Though scientists and theologians have disagreed over the age and specific event(s) that produced the petrified forests of the world, many seem to agree on the composition of the final product.  Our goal is to focus upon the petrification process that occurred after the trees were buried, and upon the colorful wonders that we see today.

(Right): Fluvial erosion at the Petrified Forest National Park.  Photo by and courtesy of Scott W. Parker ©2003

petrified_forest_np.jpg (94215 bytes)

     The references this author makes to prehistory are based both upon popular scientific
belief and upon the premise that perhaps some petrified wood formed before man.  Even many
of the world’s cultural creation scenarios agree that plants existed before mankind; therefore,
it could be possible that some petrified wood could have formed before, as well.

Gingko-Blaetter.jpg (24924 bytes)      Let’s look at a couple of examples.  One wood that is still known today, living in some of earth’s forests, is Gingko.  The Gingko Petrified Forest State Park located on the Columbia River in Washington State hosts Miocene (5.3 to 23.8 mya) Ginkgos (Gingko biloba).[xii]

(Left): Gingko biloba leaves
Photo courtesy of Reinhard Kraasch

     Another is the Mississippi Petrified Forest boasts Eocene Epoch (Tertiary) 36 million
year old wood.  These primeval remnants of perhaps a bald cypress forest (a tree known
today) lay testament to the passage of time
.  Palmwood occurs around Louisiana.

Palmoxylon.jpg (24660 bytes) palm40.jpg (8988 bytes)
Palmoxylon, Louisiana
Photo courtesy of Dr. Stephen Ervin
2.5" Diameter Palmwood Sphere, Lousiana/Texas
Photo by and courtesy of SpheresToYou.com   ©2006

The Geologic Time Scale (USGS)

     Many other species lie extinct, with evidence of their existence only culled from the
fossil record.  This month, we will leave them lie, in favor of space for more descriptive
pictures.  I will introduce some of Linnean scientific names, so that they will appear more
familiar to you in our next excursion.  Next month, we’ll uncover more about paleobotany
and plant taxonomy.

Other_Odessa_Log.jpg (250363 bytes) transpalm.jpg (10379 bytes)
Petrifed wood in the field, Odessa, Delaware
Photo by and courtesy of Gene Hartstein ©2006
2.5" Diameter Palmwood Sphere, Lousiana/Texas
Photo by and courtesy of SpheresToYou.com   ©20

     Next, let’s move ourselves out west. Put on your sunglasses and sunscreen; we'll need them.

     In many western states, falling volcanic ash covered living trees in thick sedimentary
layers.  Over time, iron- and silica-laden groundwater seeped into wood cells, thus causing
the mineral(s) to replace cell walls.  This gives us the brightly colored quartz logs we see
today.  Perhaps the heat of lavaflows hastened the process in some closer to the volcanic
cone.

     In the Petrified Forest National Park, geologic uplifting of the Colorado plateau,
sedimentary erosion, and the surficial freeze-thaw cycle produces the fractured stone logs,
as pictured here.[xiii]

making_of_petrif_forest.jpg (15162 bytes) pfnp1.jpg (18187 bytes)
A colorful landscape of fallen petrified logs inspires the artist.
A lone log draws our attention from the buttes on the horizon.
Scott W. Parker's Petrified Forest National Park Project  ©2006

     Silicification is the main process forming petrified wood, though others exist.  For example,
coalification, calcification, and pyritization, happen, too.  So, how do these other processes
compare to
silicification?

     Coalification and bogs predominated the eastern climate, like in the massive coal areas
of Pennsylvania and Ohio, so fewer petwood areas were created for us to see now. Some
form seams, other more acidic conditions can produce “coal balls”.   As erosion and uplifting
are key factors in releasing or exposing the layers in which lithified logs loom, our eastern
paleoclimate
brought less to the surface for us to dig.

     The exceptions are the present mountainous areas in the east, such as the Appalachian
Range.  It’s orogeny pushed rock containing our favored fossil to collectable depths. 

  (See the list of states just below)

     When logs are calcified, the resultant stones are white.  Upon exposure to the sun’s
UV rays over time,
they turn to a dark brown/black.[xiv]

     Opalization is similar to silicification, in that quartz is the major constituent.  The addition
of some water in the quartz matrix gives rise to the multi-hued effect.

     Pyrite and marcasite (iron sulfides) can replace wood cells, but essentially leave a cast
of the basic wood form.  The environment for change can be clay burial or an introduction
of seawater.

Locations

     According the the U. S. National Park Service, petrified wood is found in all 50 states,
and in many countries.[xv]

     One of my favorite online mineral databases, mindat.org, has listed 352 locales around
the globe.  Jolyon Ralph has tallied these U. S. states as documented locales: AL, AZ, AR,
CA, CO, CT, FL, GA, ID, IL, IA, KY, LA, MD, MS, MO, NE, NV, NM, NC, ND, OH, OK, OR,
PA, SC, TN, TX, UT, VA, WA, WV, WY.[xvi]  That’s 33 states!

     Most petrified forests in the U. S. can be found in the western part of the country.  The
most eastern is in Mississippi.  So, the best collecting opportunities abound out west.  Let’s
visit some of them!

bfsu6.jpg (85776 bytes) tmlm0001c.jpg (10938 bytes) bbf1.jpg (80715 bytes)
Blue Forest Wyoming
Photo courtesy of sticks-in-stones.com
A 1,247 lb. blue log from Indonesia
Photo courtesy of Larry Hauser
Blue Forest, Wyoming
Photo courtesy of sticks-in-stones.com

     United States law prohibits collection of fossil, rock, and mineral materials from National
Parks and Monuments, unless specifically permitted.  Each state, county, town, or area has
their own rules pertaining to their public spaces, as well.  It’s always best to study a guidebook,
a reliable websource, and inquire locally.

     We can access these online museums and sites on our laptops and PDAs in between
stops as we roll down the road:

Museums (Actual & Online)


Mineral and Lapidary Museum of Henderson County, Hendersonville, North Carolina
The Petrified Wood Gallery, Ogalalla, Nebraska
Sierra College Natural History Museum, Rocklin, California
Yale Peabody Museum Exhibition: “Petrified Wood: Rainbows in Stone”, Boston, Massachussetts
Nearartica’s Links to Natural History Museums by State and Province (U. S. & Canada)
Smithsonian National Museum of Natural History, “Geologic Time: The Story of a Changing Earth”
The Petrified Forest, Calistoga, California

     We will visit just a few of the various and sundry places.   You’ll have to make side trips
on your own, as we have only four short weeks this month to explore, before we are ready to
travel to other continents.  (Yes, even to Antarctica!)  Well, here they are:

Arizona

     Home to our featured locale, the Petrified Forest National Park, Arizona, boasts some of the
more prevalently displayed petrified paleoforest landscapes on earth!  Look below.  Could these
two photographs taken by two different photographers at two different times be of the same logs?

PetrifiedForestNationalParkArizona2.jpg (188352 bytes) pet_for2.jpg (20514 bytes)
Fractured log in the Petrified Forest National Park, Arizona
Photo by and courtesy of Dr. Stephen Ervin  ©2006
Fractured log in the Petrified Forest National Park, Arizona
Photo by and courtesy of Scott W. Parker ©2003

     Much of the area was set aside by President Theodore Roosevelt in 1906 as a National
Monument.  In 1962, it became a National Park.[xvii]

     Today, it is still tradition for any seated U. S. President to declare a National Park to
conserve important lands and landmarks for the future
By act of the State Legislature,
Araucarioxylon arizonicum
is a fossil conifer that is the state fossil of Arizona.”[xviii]

Petrified_Wood_6.jpg (11375 bytes)

Petrified_Wood_7.jpg (12867 bytes)
Araucaria_Arizona.jpg (55123 bytes) Specimens of Araucaria arizonicum

(Far Left): Log in situ at the
Petrified Forest National Park, AZ
Photos by and courtesy of
Chris and Candida Provencher
©2006

(Left): Colorful slab from Arizona
Photo by and courtesy of
Gene Hartstein
©2006

     Together, these proclaimed symbols account for an historical place of grand note for all
of us to visit and enjoy.  With an unspoiled landscape, our roving eye might have us envision
a past, living environment.  Tall trees swaying, and earth-shaking creatures walking out of
past times, might spur us to move quickly, to avoid being trampled by these--
dinosaurs! 
At any time, we can open our minds eyes to the
possibility, or return to our current beauteous
desolation.  With this exercise, we have developed our “paleo-view”, to help us understand
more about our world.

     Here, our “paleo-viewpoint” shows us that, “In the Triassic period, this species of tree
flourished in what is now known as the Black Forest, part of the 37,851 ha (93,492-acre)
Petrified Forest National Park in eastern Arizona. Prehistoric Arizona was a flat stretch of
tropical turf in the northwest corner of a supercontinent known to modern geologists as
Pangaea.”[xix]

     "Many of the fossilized logs are from a tree called Araucarioxylon arizonicum. Two
others, Woodworthia and Schilderia, occur in small quantities in the northern part of the
park. All three are now extinct.”[xx]
"

Schildera.jpg (26942 bytes) mad19.jpg (52157 bytes)
Schilderia from Arizona
Photo by and courtesy of Dr. Stephen Ervin  ©2006
Woodworthia from Madagascar
(Though not from Arizona, it does represent the species)
Photo by and courtesy of
sticks-in-stones.com   ©2006

     The park has seen man venture across its vastness over millennia, since the end of the
dinos.  From the Anasazi, Mogollon, and Sinagua peoples up to 10,000 years ago, to the
sixteenth-century Spa
niards, up to modern times, many explorers and natives alike have
walked the park.[xxi]

     Some Native American oral history recounts the role that petrified wood played in the
grand scheme.  (We will visit these stories in our next installment, so stay tuned.)

     Now, with a brief history and new perspective to our lovely land, let’s feast our eyes on
it’s wonders!  Look out the windows, this is what you will see.  We’ll disembark, so everyone
take a bag lunch as you leave the bus.

Petrified_Wood_4.jpg (9983 bytes) Petrified_Wood_3.jpg (9062 bytes) pfnp2.jpg (13955 bytes)
Petrified_Wood_1.jpg (10557 bytes) Petrified_Wood_2.jpg (10638 bytes)
Petrified Forest National Park
Photos by and courtesy of Chris and Candida Provencher ©2006
Petrified Forest National Park
Photo by and courtesy of Scott W. Parker ©2003

     If you like, we can employ any of these Touring Websites about the Petrified Forest
National Park:

Petrified Forest National Park, Arizona
White Mountains Online
Holbrook, Arizona, city of the Petrified Forest
Park Vision
DesertUSA

petforestmovie.jpg (64712 bytes)