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July 11, 2026
We have been lucky in acquiring some fantastic specimens this summer via private collections, public sales, and the two Oregon shows. Thanks for your patronage Beth and Jim ------ Friends of Fossil Forests You are welcome to attend Jim's Zoom presentation on July 14th: OPALIZED WOOD FROM CLOVER CREEK, IDAHO: A Case Study in the Power of Amateur–Professional Collaboration RSVP: https://forms.gle/N9SkaPmzyaVH7dsY7 July 14th 11:00 AM ET (Eastern Time) * be sure and convert to your local time ------------------------ The Friends of Fossil Forests is a group which encourages research and conservation, and connects professionals and amateurs interested in petrified forests. |
Welcome to Mills Geological quality identified petrified wood and plant fossils from around the globe |
Our Featured Specimen
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Agate limb cast (Incertae sedis)
Late Tertiary
Aceh Region, Sumatra Island, Indonesia
** Limb casts: The good ones are hard to find and easy to love. Just take this into hand and tell us that it is not a fantastic piece. You cannot! The casts from Indonesia don't get as much attention as the silicified wood with preserved anatomy. But they absolutely should because they are part of the volcanic story of Indonesia. Casts are formed by branches or limbs of wood encased within hot volcanic lahars but if the lahar is too hot, the wood will incinerate and disappear leaving behind only the surrounding impression of the original branch. A little-known fact here: lahar is a word originally derived from the Indonesian language in Java and it means a flowing, usually violent, mass of material ejected from a volcanic vent which combines with water and whatever soil and vegetation is in the area to create a hot mudflow concentrating in rivers or smaller stream channels. If they have sufficient gradient, they can be exceptionally destructive. Imagine a hot, viscous mudflow with the consistency of wet concrete and you can get an image of what a lahar would look like. The lahar picks up anything in its way - either destroying it or taking it along for the ride. The exterior of this specimen shows some of the original wood-like character, but long after its formation, it was also river-worn which softened the appearance. It remains a beautiful fortification agate of darker colors reflecting a preponderance of iron and manganese chromophores entrapped within the silicon dioxide tetrahedrons. This is simply a beautiful specimen with a great story to tell. This piece comes out of the Charles Eastman collection and we have left his accession tag (E959) on the unpolished end – for you to record in your accession records!
2.25" x 1.25" on polished face, limb section 2.5" long $59
Late Tertiary
Aceh Region, Sumatra Island, Indonesia
** Limb casts: The good ones are hard to find and easy to love. Just take this into hand and tell us that it is not a fantastic piece. You cannot! The casts from Indonesia don't get as much attention as the silicified wood with preserved anatomy. But they absolutely should because they are part of the volcanic story of Indonesia. Casts are formed by branches or limbs of wood encased within hot volcanic lahars but if the lahar is too hot, the wood will incinerate and disappear leaving behind only the surrounding impression of the original branch. A little-known fact here: lahar is a word originally derived from the Indonesian language in Java and it means a flowing, usually violent, mass of material ejected from a volcanic vent which combines with water and whatever soil and vegetation is in the area to create a hot mudflow concentrating in rivers or smaller stream channels. If they have sufficient gradient, they can be exceptionally destructive. Imagine a hot, viscous mudflow with the consistency of wet concrete and you can get an image of what a lahar would look like. The lahar picks up anything in its way - either destroying it or taking it along for the ride. The exterior of this specimen shows some of the original wood-like character, but long after its formation, it was also river-worn which softened the appearance. It remains a beautiful fortification agate of darker colors reflecting a preponderance of iron and manganese chromophores entrapped within the silicon dioxide tetrahedrons. This is simply a beautiful specimen with a great story to tell. This piece comes out of the Charles Eastman collection and we have left his accession tag (E959) on the unpolished end – for you to record in your accession records!
2.25" x 1.25" on polished face, limb section 2.5" long $59
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Maple (Acer sp.)
Laney Shale Member, Green River Formation, Eocene
Blue Forest, Wyoming
** A really attractive specimen with a nice pattern created by lenticular cavities filled with blue agate. The wood itself must have undergone tremendous tectonic pressures prior to petrification. The squiggly lines of medullary rays suggest that the once ramrod-straight rays and vessel pattern was changed forever by enormous pressures on the limb - likely when it was in a very wet and perhaps even spongy soft condition. That would imply a very thick and heavy downfall of volcanic ash squeezing the limb into seemingly impossible patterns. The vessels of this maple are at the upper end of sizes normally associated with the genus (around 90 microns). But, anatomy aside, what we really like is the pattern - perfect for any display shelf and cut as a standup specimen so that it does not need any additional holder to be perfectly displayed. If you are interested in the taphonomy and mineralogy of petrified woods from Eden Valley, you can check out the lengthy article in the publication Geosciences that I coauthored in 2019 with George Mustoe and Mike Viney entitled “Mineralogy of Eocene Fossil Wood from the Blue Forest Locality, Southwestern Wyoming, United States.” It is open access and can be downloaded at https://www.mdpi.com/2076-3263/9/1/35 The article can explain, in detail, the complex process that resulted in specimens like this one.
2.25" x 2" on polished face, standup that varies from 1.25" to 2.5" $45
Laney Shale Member, Green River Formation, Eocene
Blue Forest, Wyoming
** A really attractive specimen with a nice pattern created by lenticular cavities filled with blue agate. The wood itself must have undergone tremendous tectonic pressures prior to petrification. The squiggly lines of medullary rays suggest that the once ramrod-straight rays and vessel pattern was changed forever by enormous pressures on the limb - likely when it was in a very wet and perhaps even spongy soft condition. That would imply a very thick and heavy downfall of volcanic ash squeezing the limb into seemingly impossible patterns. The vessels of this maple are at the upper end of sizes normally associated with the genus (around 90 microns). But, anatomy aside, what we really like is the pattern - perfect for any display shelf and cut as a standup specimen so that it does not need any additional holder to be perfectly displayed. If you are interested in the taphonomy and mineralogy of petrified woods from Eden Valley, you can check out the lengthy article in the publication Geosciences that I coauthored in 2019 with George Mustoe and Mike Viney entitled “Mineralogy of Eocene Fossil Wood from the Blue Forest Locality, Southwestern Wyoming, United States.” It is open access and can be downloaded at https://www.mdpi.com/2076-3263/9/1/35 The article can explain, in detail, the complex process that resulted in specimens like this one.
2.25" x 2" on polished face, standup that varies from 1.25" to 2.5" $45
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Various names in commercial lumber (Sideroxylon sp.)
Little Butte Formation, Mehama Volcanics unit, Oligocene Ames Creek area, Sweet Home Petrified Forest, Linn County, Oregon ** The Genus Sideroxylon is just one of almost innumerable taxons of really hard and strong woods called "ironwood" in the modern-day commercial lumber trade. We are not using that commercial term because "ironwood" in rockhound parlance refers to petrified wood from the Palm Spring Formation found on the terraces on both sides of the Colorado River in far southern California and Arizona. There is an interesting story behind this identification. In her seminal article about petrified woods in Oregon, Irene Gregory listed Reptonia as one of about 50 genera she had identified. If you are not familiar with Irene Gregory, she was a professional paleobotanist and she formed the Beaver Hood Company in the 1970s specifically to sell identified petrified wood specimens. For years, I wondered why Reptonia was not included on the Insidewood website - eventually learning that it is a botanical synonym for Sideroxylon and also for Bumelia. Both of these genera do get hits on Insidewood, and I think the closest match to this specimen is Sideroxylon obovatum (https://insidewood.lib.ncsu.edu/description?59) which is now a South American species. While the modern South American wood seems to have more parenchyma than this Sweet Home specimen, it is otherwise quite similar. There are also several other species of Sideroxylon which are now found in Mexico and Central American, but unfortunately many of these do not have any photomicrographs on the Insidewood site to accompany their descriptions. But remember that the international rules of paleobotany require that in order to assign a fossil wood to a living species, one must have a matching reproductive structure ATTACHED to the wood since all living species are identified by their reproductive structure, not by their wood anatomy. Since we don't have an attached reproductive structure, this slab would be properly designated Sideroxylon sp. Note in the photomicrograph that the vessels are exceptionally tiny and occur in long sinuous swarms without any interruption by annual growth rings (which are very difficult to see but they can be seen as a faint seasonal line on the photomicrograph) and without obvious medullary rays. It's hard to know if this is a rare taxon at Sweet Home or not since I went several years not knowing what it looked like. But I can say that I only recently began seeing and identifying some of it after learning that Reptonia in Irene Gregory's published list of species is a botanical synonym for Sideroxylon and is now listed as such on Insidewood. In the past I would simply have called it an odd dicot wood ... 2.25" x 1.5" on the polished face; limb section 3" long $55 |
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Black Locust (Robinia zirkelii synonym Robinia alexanderii)
Ricardo Formation, Pliocene
Last Chance Canyon, California
** Here is a Black Locust specimen with an interesting taxonomic history from Last Chance Canyon, north of Mojave, California. The species Robinia alexanderii was erected by Irma Webber in her study entitled Woods from the Ricardo Pliocene of Last Chance Gulch, California published by The Carnegie Institution of Washington as Publication 412 in June 1933. At the time, Webber pointed out that it was the very first fossil record of the occurrence of Robinia in the Western USA. It is worth pointing out that Webber cited that in the fossil record, only the leaves and seed pods of Robinia had been discovered in the Eastern USA so this was also the first record of any fossil wood of Robinia anywhere in the USA! The scientific name Robinia alexanderii lasted until 1977 when Matten and Gastaldo subsumed all fossil woods of Robinia into the new species Robinia zirkelii because all fossil woods of Robinia discovered by then were indistinguishable from one another. But we like to point out that Webber's description of the Last Chance fossil wood is the one that started the entire history.
The petrified forest at Last Chance Canyon in the El Paso Mountains was completely depleted by rockhounds and souvenir hunters long before the State of California established Red Rock Canyon State Park in this area, and subsequently added Last Chance Canyon to the park. So, even if there were more petrified wood there now (there isn't), you would not be allowed to collect it! This piece was collected in the 1960's by a rockhound from Southern California. The descendants of this genera are still alive and well in North America and are often found in the west along the banks of rivers and smaller perennial streams. Simply a great piece with a history of the taxon from a locality severely depleted by the middle of the 20th Century and now part of the California State Park System
2.25" x 1.25" on the polished face; it is cut as a parallel standup specimen 2.25" tall $35
Ricardo Formation, Pliocene
Last Chance Canyon, California
** Here is a Black Locust specimen with an interesting taxonomic history from Last Chance Canyon, north of Mojave, California. The species Robinia alexanderii was erected by Irma Webber in her study entitled Woods from the Ricardo Pliocene of Last Chance Gulch, California published by The Carnegie Institution of Washington as Publication 412 in June 1933. At the time, Webber pointed out that it was the very first fossil record of the occurrence of Robinia in the Western USA. It is worth pointing out that Webber cited that in the fossil record, only the leaves and seed pods of Robinia had been discovered in the Eastern USA so this was also the first record of any fossil wood of Robinia anywhere in the USA! The scientific name Robinia alexanderii lasted until 1977 when Matten and Gastaldo subsumed all fossil woods of Robinia into the new species Robinia zirkelii because all fossil woods of Robinia discovered by then were indistinguishable from one another. But we like to point out that Webber's description of the Last Chance fossil wood is the one that started the entire history.
The petrified forest at Last Chance Canyon in the El Paso Mountains was completely depleted by rockhounds and souvenir hunters long before the State of California established Red Rock Canyon State Park in this area, and subsequently added Last Chance Canyon to the park. So, even if there were more petrified wood there now (there isn't), you would not be allowed to collect it! This piece was collected in the 1960's by a rockhound from Southern California. The descendants of this genera are still alive and well in North America and are often found in the west along the banks of rivers and smaller perennial streams. Simply a great piece with a history of the taxon from a locality severely depleted by the middle of the 20th Century and now part of the California State Park System
2.25" x 1.25" on the polished face; it is cut as a parallel standup specimen 2.25" tall $35
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Primitive Conifer (Araucaria Family)
Chinle Formation, Triassic North of Winslow, Arizona ** We might have to go so far as to call this specimen bedazzled – because who couldn't love a specimen of Arizona wood with this unusual covering of sparkling quartz crystals? This new find, on a private ranch north of Winslow, was a feature at the Tucson Show this year. The deposit contained the petrified remains of only two trees -- both of them having extraordinary coatings of smoky and white quartz crystals that formed in desiccation cracks and cavities in the original trees which must have been dead and down for a lengthy period of deterioration prior to becoming covered with volcanic ash and subsequently fossilized. The vast number of specimens available for purchased consisted of almost exclusively the quartz crystals with very little of the wood character remaining. Only two full rounds were recovered from the dig. One of the full rounds had already gone to the University of Arizona, Alfie Norville Mineral Museum, in Tucson. The other full round was quite large (9" diameter and 18" long) and priced at $12,500 so we left it with the dealer hoping it might end up being acquired by a different museum. But this piece has even better presentation of wood character and sparkling quartz than did the full rounds. The glittery coatings on this wood proved particularly difficult for us to photograph, but we hope that you get the feel for how much sparkle this extraordinary specimen has to offer. Summer is here. Put this specimen in a sunny window, on your porch or patio or in some good light in your home. You will not be disappointed. This piece has the best combination of wood character and quartz crystals of any of the specimens, even better than the full round that we left with the dealer. The contrast of smoky and white quartz crystals makes for a great display. The piece also offers some other great features including a knot where a small branch was emerging and several spots we interpret as the beginnings of the Polyporites wardii fungal growths. There is some remaining excellent preservation of the Araucaria tracheids - a feature absent in almost all other the specimens the dealer had to offer. In summary, this specimen is quite unique for Arizona Chinle formation wood. Looking back in history, we note that the Petrified Forest National Monument (now National Park) was set aside in 1908 by Teddy Roosevelt to stop the wanton blasting of petrified logs in order to obtain crystals of amethyst and quartz for manufacture into jewelry. So, this specimen also reflects on an historical anecdote, being from the same Chinle Formation but 50 miles to the west of today's National Park! If you strive for aesthetics in your petrified wood collection, along with excellent provenance, this is a fine candidate to acquire. 4.25" x 2" in cross section; 6.5" in length $595 (… and therefore immediately qualifies for our 10% discount on orders totaling $200 or more) |
Polyporites structure on flat side of specimen
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Pepper tree (Schinoxylon actinoporosum)
Laney Shale Member, Green River Formation, Eocene Blue Forest, Wyoming ** Don't you just love the blue and gray botryoidal agate along the entire length of this limb section? Yes, that is a perfect description of this amazing piece. To make for a perfect display our lapidary cut off a bit of the end and then polished both of the cut faces - limb and end cut. That way it can be displayed numerous ways with always the possibility of showing the cut and polished face. The blue agate is simply among the best we have seen for quite some time and it complements the brown wood perfectly. It takes several photos to show just how covered over with blue agate this beauty is so if you are inclined towards aesthetic specimens, this one is for you; you have found a fantastic new specimen to add to your collection. 2” diameter on each cut and polished face, 3.25" in length limb section, .75" end cut $240 (and therefore immediately qualifies for our 10% discount on order totaling $200 or more) |