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May 7, 2025
Happy Spring! More wood on the way soon ... Beth and Jim ----- And if you haven't already done so, join Friends of Fossil Forests, a group which encourages research and conservation, and connects professionals and amateurs interested in petrified forests. ------ Jim Mills and Beth Myers |
Welcome to Mills Geological quality identified petrified wood and plant fossils from around the globe |
our featured specimen
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Legume (Fabaceae Family, Caesalpinioidea Subfamily)
Yegua Formation; Eocene Chambliss Ranches, Madison County, Texas ** This is a beautiful slab from the old collection that has provided us with so many really excellent specimens with perfect provenance! Ahhh, the third largest family in the plant kingdom actually goes by two different names; Fabaceae and Leguminosae families are the same thing. We sometimes marvel at the degree to which botanists have subdivided species and other taxons on the basis of seemingly very small differences so it always brings a smile when we see the exact opposite - indecision as to which name is preferred. So, we have simply cited BOTH, just like the best of botanists! A quick check on Wikipedia reveals that it is NOT for lack of variety that the family is known by two names; there are 765 genera and over 20,000 species that have been described ... so far! Caesalpinoideae is one of the taxons that have been identified in other Texas locations of the Yegua Formation. The Caesalpinoideae subfamily is so large that it is broken up into at least eight clades plus subclades and dozens of genera. The difference between many of their wood anatomies are often discernible only by cutting specimens into the three different planes (Transverse, Radial, Tangential) and our specimen is only cut on the transverse plane. Obviously, we are not willing to slice up our specimen in the diamond saw, so we will have to settle for identifying it only down to the subfamily level. Check out the photomicrograph and take immediate notice of the vasicentric parenchyma surrounding the vessels. There seem to be a lot of vessels but an oddity of statistics is that their very large size, including the vasicentric parenchyma, means that they have a relatively small number per square millimeter. We often associate low densities of vessels with very small, very sparse vessels in wood but in this case, the large size makes for low density even though they really look "crowded" in our photomicrograph. The aesthetics of this specimen alone make it a desirable addition to collections of fine fossil wood. In sum - we really like this slab! 7” x 5” on polished face; 7/8” thick slab $90 |
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Conifer (Pinales Order)
Late Eocene
Hen Egg Mountain, Brewster County, Texas
** An unusual locality for any collector. It took quite a while but a determined search with a microscope finally found a few spots with discernible tracheids diagnostic of a conifer. Hen Egg Mountain is located north of Terlingua, Texas and roughly in between Big Bend National Park and Big end Ranch State Park. It is one of those areas that the National Geologic Map Data Base does not identify a measured Formation name but instead identifies a lithologic unit. This unit is called the Tuff of Hen Egg Mountain and it is a highly silicified rhyolite of late Eocene age (approximately 40.4 to 41.2 Ma). Highly silicified rhyolites are a "sweet spot" for contributing the silica necessary to petrify any existing wood that may have been covered by an explosive volcanic event. Even if the geology does not get you excited, the odd name Hen Egg Mountain should capture your interest. Texas history never seems to fail coming up with odd and unusual place names. Perhaps it is because the state is so large, they had to come up with odd names because there were so many places to name!
6.75" x 5.75" on polished face; slab 1/2" thick $60
Late Eocene
Hen Egg Mountain, Brewster County, Texas
** An unusual locality for any collector. It took quite a while but a determined search with a microscope finally found a few spots with discernible tracheids diagnostic of a conifer. Hen Egg Mountain is located north of Terlingua, Texas and roughly in between Big Bend National Park and Big end Ranch State Park. It is one of those areas that the National Geologic Map Data Base does not identify a measured Formation name but instead identifies a lithologic unit. This unit is called the Tuff of Hen Egg Mountain and it is a highly silicified rhyolite of late Eocene age (approximately 40.4 to 41.2 Ma). Highly silicified rhyolites are a "sweet spot" for contributing the silica necessary to petrify any existing wood that may have been covered by an explosive volcanic event. Even if the geology does not get you excited, the odd name Hen Egg Mountain should capture your interest. Texas history never seems to fail coming up with odd and unusual place names. Perhaps it is because the state is so large, they had to come up with odd names because there were so many places to name!
6.75" x 5.75" on polished face; slab 1/2" thick $60
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Pepper tree (Schinoxylon actinoporosum)
Laney Shale Member, Green River Formation, Eocene Blue Forest, Wyoming ** You already have a specimen of Schinoxylon in your collection? Not surprising! But this one is a bit different because it is a small and perfect piece. The wood itself is a complete, absolutely perfect round with all of the bark (phloem) separated from the wood (xylem) by luminous agate which is punctuated by two fine fortification patterns. While our photograph doesn’t do it justice, the agate is translucent and gorgeous. At 55 mm in diameter, this specimen falls into the "miniature" specimen category used by mineral collectors (i.e. between 30mm and 64mm in maximum size). You won't find a better representative of perfection than this one in an Eden Valley "mini" specimen. 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 perfect specimens like this one. 2.25” in diameter on polished face; 3/16" thick slab $54 |
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Opalized wood - Poplar (Populus sp.)
Truckee Formation, Pliocene Sam Swartz Ranch, Hazen, Nevada ** An outstanding slab with excellent colors and beautiful pattern. The Sam Swartz Ranch at Hazen, midway between Fallon and Fernley in Nevada was a popular fee area for rockhounds in the mid-20th century. There were digs on both sides of U.S. Highway 50 on his ranch lands and he was mentioned in magazine articles as an affable host to rockhounds. Much of the opalized wood recovered from his ranch had distinguishing features of a sandy ash coating on portions of the exterior and highly opalized permineralization in various hues of brown, yellow, and white. After Sam passed away, the ranch was sold and all rockhounding came to an abrupt end. It never restarted - but the specimens recovered during his lifetime and are currently residing in older collections are being redistributed to a new generation of collectors – which is how it should be. A lot (and we mean a LOT) of the opalized wood went into costume jewelry since it possessed that particular glassiness typical of common opal which takes such a good polish. There is hardly any remaining wood structure in the highly opalized center but there are patches of good preservation in and near the white periphery. See our photomicrograph to view the crowded, small (around 50 microns) vessels. Here's an opportunity to carry on the tradition started by Sam by adding a particularly beautiful specimen of poplar to your own collection. 3.25" x 2.5" on polished face, slab varies from 1" to 1 1/2 " thick $45 |
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Undetermined Root (Incertae sedis)
Tertiary Chimney Creek, Nevada ** This is a real "killer" display specimen! It is a main root with numerous root protuberances now seen as rootlets, bumps and swellings emanating from the main axis. Most of the material recovered at Chimney Creek Reservoir is root, not stem, and this section is no exception. But it is exceptional in its character. Growth habits of roots generally preclude sending rootlets in the direction of the sky, a phenomenon caused by both gravity and the relative difference between soil moisture above and below the main root axis. However, if the root is deep enough it will send rootlets in every direction in search of water and nutrients. We love the display quality of the piece with perfect polish on the cut face and outstanding character along the exterior. 1.5" x .75" on polished face, 6.5” long section $85 |
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Ancient conifer (Gymnosperm)
Brushy Basin Member, Morrison Formation (Late Jurassic)
Henry Mountains area, Utah
** Looking for an archetypal specimen to add to your collection? This Henry Mountains specimen is the definition of typical with black and brown highlighted with red agate inclusions along the desiccation cracks. This log was well along towards becoming just vegetative debris on the forest floor when a volcanic event luckily saved it just in time for future petrified wood collectors. That historical analysis should tell you that the structure of this slab is not of the perfection that would send a paleobotanist right to the computer keyboard to write an article. Instead, it would be of more interest to those collectors who value the patterns and color pathways created by bacterial and fungal activity after the tree is dead and down. Fortunately, those bacteria and fungus were stopped dead in their tracks just in the nick of time when buried by volcanic ash in the Late Jurassic. No oxygen meant no more destruction and soon, groundwater carrying silicic compounds along with traces of iron oxides began the process of permineralization. We really love these slabs that tell their own colorful story.
4" x 3.5" on polished face; 7/16" thick slab $59
Brushy Basin Member, Morrison Formation (Late Jurassic)
Henry Mountains area, Utah
** Looking for an archetypal specimen to add to your collection? This Henry Mountains specimen is the definition of typical with black and brown highlighted with red agate inclusions along the desiccation cracks. This log was well along towards becoming just vegetative debris on the forest floor when a volcanic event luckily saved it just in time for future petrified wood collectors. That historical analysis should tell you that the structure of this slab is not of the perfection that would send a paleobotanist right to the computer keyboard to write an article. Instead, it would be of more interest to those collectors who value the patterns and color pathways created by bacterial and fungal activity after the tree is dead and down. Fortunately, those bacteria and fungus were stopped dead in their tracks just in the nick of time when buried by volcanic ash in the Late Jurassic. No oxygen meant no more destruction and soon, groundwater carrying silicic compounds along with traces of iron oxides began the process of permineralization. We really love these slabs that tell their own colorful story.
4" x 3.5" on polished face; 7/16" thick slab $59
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Rattan Palm (likely Calamus sp.)
Bridger Formation; Eocene Big Sandy Reservoir, near Farson, Wyoming ** A spectacular short length section of a palm also called "cane" palm or "cluster" palm. Great wood anatomy structure (see photomicrograph) when viewed on the polished face end, and a small cavern of wonderful chalcedony stalactites when viewed from the natural end and exterior length shows the node - a feature that indicates it likely had a liana growth habit! What more could you want from a cluster palm? Another very nice specimen from the collection of the late Charles Eastman. There are over 400 modern species of rattan palms assigned to the genus Calamus in the Arecaceae Family of palms. Some of them are liana-type, growing vine-like and climbing other plants with stronger and wider trunks. Others are cluster-type, with several stems growing from a common root mass. Unlike the larger fossil palm trunks from the Big Sandy area, these rattan palms almost never have any algae preserved on the exterior indicating that they have a different taphonomy than the large palm trees. The large palms were immersed in water allowing algae to grow on their exterior while the rattan palms could not have been under water in an environment conducive to algae growth. Oddly and sadly, the term "cane" palm originated from the practice of using sections of these stems for corporal punishment (i.e. "caning”), a practice that still goes on in some schools and military organizations in various Southeast Asian countries. 7/8" diameter on the polished face, 3.75" in length $49 |
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Joshua Tree (Protoyucca shadishii) Virgin Valley Formation, Miocene Badger Flat, Humboldt County, Nevada ** This is a very unusual presentation of one of the scarcest species of petrified wood that one can collect. We have highlighted two separate closeup photomicrographs to demonstrate the point. This Joshua Tree was already dead and down when the volcanic event buried it under a layer of volcanic ash. Note the difference in the structure of the vascular bundles in each picture. In one the vascular structure is well-organized and seems to have been functioning properly but in the other picture you see the vascular structure disorganized and in fact, many small pieces of broken strands seem to predominate. Next notice that there is a wide cavity of white chalcedony that has no remaining anatomical structure. Quite typically, this plant suffered mightily from heartrot - a common problem for monocots since they lack the ability to produce toxins that can ward off fungal attacks. Monocots send up only one cotyledon from the seed rather than two - and silicified petrifications of monocots are very rare in the fossil record (palm is the single exception to this fact). And, as you can plainly see, this piece has the added benefit of some beautiful fortification agate! 5" x 3" on polished face; end cut varies from 1/2" to 1" thick $75 |
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Araucaria Family (Araucariaceae)
Chinle Formation, Sonsela Member; Triassic
Long H ranch, near St. Johns, Arizona
** Fabulous pattern suggestive of the radial grain - and a feathery pattern that you can see from across the room! What looks like annual growth rings are more likely to be periodic drought rings. The environment during Chinle Time of the Triassic was quite sub-tropical - warm and wet but of course, droughts happen and cause a temporary cessation of growth. Please note that there is a tiny bit of edge damage at the 6:00 o'clock position. It is easier to see on the unpolished back side and not so much on the polished front side. However, it is a bit of damage and thus resulted in a real bargain price from the cutter. We are passing that savings along. In the absence of any edge damage this slab would command a price at least twice what we are able to ask. And it is gorgeous by the way.
9" x 7" on polished face; 5/8" thick slab $55
Chinle Formation, Sonsela Member; Triassic
Long H ranch, near St. Johns, Arizona
** Fabulous pattern suggestive of the radial grain - and a feathery pattern that you can see from across the room! What looks like annual growth rings are more likely to be periodic drought rings. The environment during Chinle Time of the Triassic was quite sub-tropical - warm and wet but of course, droughts happen and cause a temporary cessation of growth. Please note that there is a tiny bit of edge damage at the 6:00 o'clock position. It is easier to see on the unpolished back side and not so much on the polished front side. However, it is a bit of damage and thus resulted in a real bargain price from the cutter. We are passing that savings along. In the absence of any edge damage this slab would command a price at least twice what we are able to ask. And it is gorgeous by the way.
9" x 7" on polished face; 5/8" thick slab $55
Undetermined Root (Incertae sedis)
Tertiary Chimney Creek, Nevada ** This is a wonderful display specimen! It is a main root with numerous root protuberances now seen as bumps and swellings emanating from the main axis. Most of the material recovered at Chimney Creek Reservoir is root, not stem, and this section is no exception. Growth habits of roots generally preclude sending rootlets in the direction of the sky, a phenomenon caused by both gravity and the relative difference between soil moisture above and below the main root axis. We are told by the collector that this specimen came from an area a bit north of the traditional Chimney creek locality at the edge of the reservoir. We love the display quality of the piece with perfect polish on the cut face and outstanding character along the exterior. 1.75" in diameter on the polished face, 6” long section $35 |
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