Our featured specimen
​Conifer surrounded by algae (Pinales Order)
Miocene, Trout Creek Formation
"Green Algae Wood Site" near McDermitt, Nevada/Oregon
** It has been a long time since we have had one of these specimens to offer.  The so-called Green Algae Wood Site is just one of the many different diggings associated with the McDermitt area.  But, it has long since been depleted and specimens now only come out of old collections.  The green color results from a trivalent form of iron oxide that colors the silicon dioxide as a trace element -- not because the living algae was green.  Why this particular oxide colored only the algae and not the wood is somewhat of a mystery but it likely is the result of the algae being softer and more porous and for some reason the trivalent iron ions were only available at the very beginning of the petrification event.  Later infusions of silica were much darker as a result of bivalent iron ions and perhaps an occasional trace of manganese as well as some of the dark minerals like biotite and olivine in the ash began to weather.  If your collection does not have a representative specimen from this now depleted site, here is a chance to fill that gap.  As you might imagine, with that much algae surrounding the wood, there was not a good prospect of the wood anatomy being well preserved.  But, certainly enough remains to determine that it was a conifer.  There is a fair amount of opalization in the material from this site and this slab has been backed with a coating of resin to prevent inadvertent damage or fracturing.
7.5” x 7" on polished face; 1/2" thick slab   $160
​"Haw" or "Linden" tree  (Viburnum sp.)
Mehama Volcanics Unit, Little Butte Formation, Oligocene
Sweet Home area, Oregon
** Well, it all depends upon where you are.  Trees and shrubs of this genus in North America are called by the common name "Haw." while those in Europe are called "Linden."  Call it what you want but this specimen is exceptional.  Really fantastic preservation of woody fine structure.  Check out the photomicrograph for this one.  Note the vessels are almost entirely solitary - an occasional double but no long radial multiples.  Rays are commonly 1 to 3 cells wide but can be even wider than that - all of them are present in this specimen.  Growth rings distinct?  Check!  Vessels in the range of 50 microns, similarly sized throughout the entire growth ring?  Check!  How about density in the range of 40 to 100 per square millimeter? Check! Can you tell we think this is an exceptional specimen with great pattern and really wonderful woody fine structure?  It even has a periphery of bark (real phloem). The Sweet Home petrified forest has produced a lot of fossil wood and we think that this specimen is at the top end of high-quality.  It embodies everything that an advanced collector would want in a Sweet Home specimen.  Please click photo for a more detailed view.
7.5” diameter on polished face; 1/2" thick slab  $190
​Sycamore (Platanus sp.)
Clarno Formation; Late Eocene
Teater Ranch, near Post Oregon
** Are you looking for a Teater Ranch sycamore with loads of woody character along the exterior surfaces?  This one is a top candidate for that description.  Of course, it also has a fantastic pattern on the professionally polished face with a leaching pattern that gives it an artistic look!  The exterior wood grain character is emblematic of outstanding Teater Ranch sycamores. There is cambial impression from one end to the other -- definitely a good look.   If you are a limb section enthusiast with an eye for beauty, this one is destined for you and your advanced collection. The Teater Ranch locality has been sold again and the new owners absolutely prohibit any collecting so we now see only specimens out of old collections. 
2” x 1” on the polished face; limb section up to 4” long    $75
​Black Locust   (Robinia sp.)
Trout Creek Formation, Miocene
McDermitt, Nevada/Oregon
** A picture is worth a thousand words. Here is an outstanding slab of Black Locust (Robinia sp.) with incredibly well-defined growth rings. It also features really excellent woody fine structure (see our photomicrograph). The McDermitt area has several diggings locations within a 15-to-20-mile radius. This piece from the Bretz Mercury Mine airport site is immediately obvious, even to a novice, that it is petrified wood. That's a good thing --- whether you exhibit your collection at shows or just in your living room!  We generally identify the site as McDermitt, Nevada, which is both the closest inhabited place as well as the access point to the dirt roads leading to the diggings. However, the diggings are just across the border in Oregon (Malheur County), but it takes a GPS to find that out.  There are no signs on the dirt roads announcing "Entering Oregon."
6" x 4.5" on polished face, 3/8" thick slab   $65
Ancient conifer  (Pinales Order)
Columbia Plateau Basalts Group
Miocene
Saddle Mountain, Washington
** A very desirable limb section of what is often referred to as "Orange Rind" for the yellow-orange color of some of the edge of the cut face.  This piece has great aesthetic appeal rather than preservation of anatomy.  Yes, a very determined search does turn up a few unmistakable tracheids indicative of conifers but the real reason for having one of these specimens is the uniqueness and beauty.  It is an end cut that sits very nicely on its natural side uncut end for display.  Fantastic external morphology and attractive gray-glue agate-line cavities. 
While we have been ultra-fortunate to acquire several of these “orange rind” specimens of late, they have become very scarce and we never pass up a chance to add one to our inventory.
3" x 2.5"” on polished face; 3" thick end cut  $47
​​Conifer (Pinales Order)
Mehama Volcanics Unit, Little Butte Formation, Oligocene
Sweet Home, Oregon
** Yes, growth rings that you can see from across the room – or maybe across two rooms for this one -- one of our favorite descriptions because it is one of our favorite patterns in a petrified wood slab.  There is a lot to be said for transverse cuts that show this kind of display quality.  The most unknowledgeable observer can immediately recognize this kind of pattern as fossil wood.  It is a conversation starter and opportunity to explain the process of permineralization of trees following volcanic events that supply the silicon dioxide.  While we are not always favorably biased towards these perfectly round slabs, one of our good collector friends like to call them “bulls’ eyes” – an apt description that brings immediate mental patterns to mind.  Great rings with a blue agate slash – special! 
6" x 5" on polished face; 3/8" thick slab   $70
​Walnut  (Juglans sp.)
Tertiary
East Texas
 ** An irresistibly charming slice of wood, with soft autumnal colors and an engaging pattern.  See our photomicrograph for a good look at the woody fine anatomy.  Modern walnuts that show the diagonal pattern of vessels between annual growth rings are restricted to Asia but they were quite prevalent in the early Tertiary period of North America when conditions were considerably warmer than now.  This slice is a good example of that phenomenon.  On the other hand, some pieces are just charming and deserve a place on the shelf based upon aesthetics alone, like this piece with an unusual gray and gold mineralization.  Any other scientific attribute is just icing on the cake! 
5” x 5” on polished face’ 3/8” thick slab   $50
THE BOOKSHELF
(Books pictured are our, rather shelf-worn copies.  Yours will be brand new in wrapping.)
   As we all continue to build our knowledge of petrified wood, you are probably still building a library of books for reference.  From time to time we find excellent copies of classic books at great prices and when we do, we purchase them and pass along the savings to our friends and customers. That is the case for the present offering of three different books that came out in the 1990s that should be on hand for every collector of petrified wood. 
 
   The author Ulrich Dernbach, now retired, was a petrified wood dealer from Germany whom we met in the early 1990's.  Much of his inventory was material he had collected all over the world on trips to localities with local expert guides.  In addition to selling beautiful specimens, he wanted to share his knowledge and experiences through the publication of several books. 
 
   His first effort, entitled Araucaria, details the fossil wood of this family of trees as well as the fantastic fossil cones from Argentina.  Araucarian trees were the dominant forest components during the Mesozoic era but have since declined to only a remaining dozen or so species alive today - all native to the Southern Hemisphere.  The text and photos make this a really useful book for any fossil enthusiast.  Members of the Mesozoic Araucarian family of genera are fossilized as wood, cones, and other reproductive structures as well as foliage.  They run the gamut from silicified preservations all the way to compression/impression fossils and Dernbach covers them all.

   His second effort entitled Petrified Forests - The World's 31 Most Beautiful Petrified Forests covers spectacular petrified forests on several continents with descriptions of species found - and a bit of a travelogue about how to get to them.  If your collection includes great specimens from worldwide localities, it is almost a given that some of your localities will be covered in Dernbach's second book (sometimes called the "Blue Book" by ardent collectors).
 
   The third and final book, entitled Secrets of Petrified Plants is actually a compilation of essays by a dozen of some of the world's best paleobotanists along with introductory notes by Mr. Dernbach.  He wisely included highly respected scientists, museum curators, advanced collectors, and other specialists in his compilation of authors of the twelve essays.  Petrified wood collectors may already recognize names like Walton Wright, Don Tidwell, Ronny Rößler, Robert Knoll, Ruth Stocky, Manfred Barthel, Hans Kerp, Alfred Selmeier, Volker Wilde, Walter Jung, Jean Galtier and Gar Rothwell.  They are all experts and they all are skilled in writing for the layperson collector as well as their academic colleagues. If you like to put knowledge about your specimens into your catalog, then this is the book to use.
 
   These truly are three books that should be on the shelf and coffee table of every petrified wood collector.  They are descriptive, very well-illustrated, and aimed at the collector.  The copies we offer are brand new, still in their original wrappers.  Used copies of these out-of-print publications are generally priced at well over $60 to $75, and new copies are even more when they can be found.  We were fortunate to obtain several new, never-opened copies at a terrific price, and we want to pass those savings along to our collector friends.  The price for each book is $45. Price for the set of three is $105. (Please note that these are net prices and will not receive the 10% discount on orders over $200). The photographs we show are of copies in our own library.  Your books will arrive in their original paper wrapper (Araucaria) or plastic shrink-wrap (31 Petrified Forests or Secrets of Petrified Plants). 
​Pepper tree  (Schinoxylon actinoporosum)
Laney Shale Member, Green River Formation, Eocene
Blue Forest, Wyoming
** This one has got lots going for it in addition to this great price!  Excellent woody fine structure of the pepper tree along with a nice quartz crystal-filled cavity plus bits of bark floating in the baby blue agate around the 11:00 o'clock position.  But wait -- there's more.  Yes, easy to see borer tunnels - one of which is filled with frass (that formal botanical word meaning insect poop).  Did we mention that there is a second heart where a small stem was forming right near the frass filled tunnel?  There is simply a lot to love about this excellent specimen.  If you are a Blue Forest enthusiast, it will surely be a good fit into your collection.
3.75” x 2.5" on polished face; 3/8” thick slab  $45 
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Copyright  Mills Geological  2023
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