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January 19, 2026
The Tucson Shows beckon, but now before our departure in a week, we have many new specimens to offer. Build a cart? Thank you for your continued friendship. Jim Mills and Beth Myers ------ Check out Jim's recently-published article about silicified cattails from Lonely Butte, California, published in the Nov-Dec issue of Rocks and Minerals magazine. I'm very proud of his diligence, research and resulting accomplishment on silicified cattails from this genus and locality. Beth ------ Have you joined? 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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Yew (Taxus sp.) in Stromatolitic Algae
"Tonopah Wood" double heart
Miocene
Tonopah, Nevada
** THIS JUST IN! Beautiful “Tonopah Wood” end cut with tiny full round in the center surrounded by perfectly preserved algae. PLUS A NICE GRUP OF OSTRACODS! This smaller specimen (about 2” diameter) has a full round twig measuring only 1/4" in diameter that when seen under magnification shows superbly defined, extremely closely-packed growth rings. The surrounding algae is organized into near perfect colonies suggesting that the action took place in relatively calm lacustrine waters. Outside of the main collection of algal colonies, there is a lovely group of ostracods - again, best enjoyed with a loupe or microscope (see our selection of photomicrographs). The exterior of this specimen gives a nice view of the character of a growing algal colony. Old-timer rockhounds called these attractive specimens by the name Tonopah Wood because they came from the hills to the north/northeast of the old mining camp of Tonopah.
We have never seen any species other than Yew (Taxus sp.) from this locality and that relatively slow-growing conifer accounts for the closely packed growth rings in this twig (we note that it seems odd to use the term twig for a stick that has as many growth rings as this one has). This specimen comes out of an old collection and we have left their red magic marker notation on the natural end of the specimen even though we are unable to determine if it is a number or a set of initials. Lovely mystery - but of course easily removed with acetone or bleach if the you the new owner elects to do so.
4” diameter on dome polished face, 2" long end cut $89
"Tonopah Wood" double heart
Miocene
Tonopah, Nevada
** THIS JUST IN! Beautiful “Tonopah Wood” end cut with tiny full round in the center surrounded by perfectly preserved algae. PLUS A NICE GRUP OF OSTRACODS! This smaller specimen (about 2” diameter) has a full round twig measuring only 1/4" in diameter that when seen under magnification shows superbly defined, extremely closely-packed growth rings. The surrounding algae is organized into near perfect colonies suggesting that the action took place in relatively calm lacustrine waters. Outside of the main collection of algal colonies, there is a lovely group of ostracods - again, best enjoyed with a loupe or microscope (see our selection of photomicrographs). The exterior of this specimen gives a nice view of the character of a growing algal colony. Old-timer rockhounds called these attractive specimens by the name Tonopah Wood because they came from the hills to the north/northeast of the old mining camp of Tonopah.
We have never seen any species other than Yew (Taxus sp.) from this locality and that relatively slow-growing conifer accounts for the closely packed growth rings in this twig (we note that it seems odd to use the term twig for a stick that has as many growth rings as this one has). This specimen comes out of an old collection and we have left their red magic marker notation on the natural end of the specimen even though we are unable to determine if it is a number or a set of initials. Lovely mystery - but of course easily removed with acetone or bleach if the you the new owner elects to do so.
4” diameter on dome polished face, 2" long end cut $89
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Limb cast (Incertae sedis)
Absaroka Supergroup, Eocene
Yellowstone River gravels, Montana
** Nearly every rockhound and collector of petrified wood is familiar with the beautiful lapidary material called "Montana Agate." But many don't realize that all Montana Agate started out as enormous agate limb casts that eventually weathered out, broke up and eroded into the Yellowstone River. The clever rockhounds use a pontoon raft to slowly float down the Yellowstone River sections to the west of Miles, Montana searching the bottom for the beautiful agate. Specimens like this one are commonly believed to be the core of these ancient trees. This one is the perfect size for collectors with limited storage and display room. It is out of the Charles Eastman collection and has his accession number (E475) on the reverse side.
(The two views are similar here – just included to demonstrate that this great little cast appears subtly different in different lighting.)
1.5" x 1" on the polished face, section 1.5" long $29
Absaroka Supergroup, Eocene
Yellowstone River gravels, Montana
** Nearly every rockhound and collector of petrified wood is familiar with the beautiful lapidary material called "Montana Agate." But many don't realize that all Montana Agate started out as enormous agate limb casts that eventually weathered out, broke up and eroded into the Yellowstone River. The clever rockhounds use a pontoon raft to slowly float down the Yellowstone River sections to the west of Miles, Montana searching the bottom for the beautiful agate. Specimens like this one are commonly believed to be the core of these ancient trees. This one is the perfect size for collectors with limited storage and display room. It is out of the Charles Eastman collection and has his accession number (E475) on the reverse side.
(The two views are similar here – just included to demonstrate that this great little cast appears subtly different in different lighting.)
1.5" x 1" on the polished face, section 1.5" long $29
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Ancient Gymnosperm (Araucariaceae Family)
Windalia Radiolarite Formation, Middle Cretaceous
Mooka Sheep Station, Western Australia
** Check your collection. If you have a specimen from this locality, this one might just be superior. This specimen has extreme visual punch from the famed Mooka Sheep Station on the Gascoyne River of Western Australia – contrast that we don’t always see in these pieces. The locality is primarily noted for this so-called "peanut wood" wherein the white radiolarian chert has back-filled teredo worm borings in the wood. It is our understanding from Australian field collectors that the material that was once found on the surface over hundreds of square miles (everything is BIG in the Australian outback) has now become quite difficult to find. Whereas 30 years ago a collector could drive an ATV over several square miles (or kilometers as they use down under) and in a day find a few hundred kilos of wood, today the numbers are more like a few pieces for a full day's scouting and driving about. Consequently, we no longer see much "peanut wood" on the market from the Mooka Sheep Station and we are told by those same intrepid Australian field collectors that ranging over hundreds of square miles on an ATV in the very hot Australian sun to find only one or two pieces in a day is not productive and they now concentrate on collecting different lapidary rocks in different areas!
As a side note, in our experience over the years, the specimens showing a center of the tree, like this one, have always been a bit scarcer than the "chunks" (many of which were cut into longitudinal boards rather than transverse rounds. This specimen has a nice display on the natural side of numerous smaller teredo borings.
5" x 3.5" on polished face, end cut varying from thin edge up to 2.5" thick $115
Windalia Radiolarite Formation, Middle Cretaceous
Mooka Sheep Station, Western Australia
** Check your collection. If you have a specimen from this locality, this one might just be superior. This specimen has extreme visual punch from the famed Mooka Sheep Station on the Gascoyne River of Western Australia – contrast that we don’t always see in these pieces. The locality is primarily noted for this so-called "peanut wood" wherein the white radiolarian chert has back-filled teredo worm borings in the wood. It is our understanding from Australian field collectors that the material that was once found on the surface over hundreds of square miles (everything is BIG in the Australian outback) has now become quite difficult to find. Whereas 30 years ago a collector could drive an ATV over several square miles (or kilometers as they use down under) and in a day find a few hundred kilos of wood, today the numbers are more like a few pieces for a full day's scouting and driving about. Consequently, we no longer see much "peanut wood" on the market from the Mooka Sheep Station and we are told by those same intrepid Australian field collectors that ranging over hundreds of square miles on an ATV in the very hot Australian sun to find only one or two pieces in a day is not productive and they now concentrate on collecting different lapidary rocks in different areas!
As a side note, in our experience over the years, the specimens showing a center of the tree, like this one, have always been a bit scarcer than the "chunks" (many of which were cut into longitudinal boards rather than transverse rounds. This specimen has a nice display on the natural side of numerous smaller teredo borings.
5" x 3.5" on polished face, end cut varying from thin edge up to 2.5" thick $115
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Primitive conifer (Araucarioxylon)
Chinle Formation, Triassic
Circle Cliffs, County, Utah
** Terrific genuine old-timer here. We recently acquired specimens out of an old collection on which the collector had noted the exact location and year that the piece was collected. Circle Cliffs petrified wood is distinctive for the rich reds and rust-reds that contrast strongly with the blacks, browns and whites. That’s why we love this small slice - it has exceptional presence and is made-to-order for the collector with limited space to store and display their collection. (And maybe we all fall into that category …?) The Araucariaceae Family dominated the Mesozoic Forests.
In the case of the Chinle Formation, the forest was located in the subtropical latitudes with a mild climate and year-round precipitation. That is the reason you see so few specimens with annual growth rings. Like the tropical and subtropical species today, those giant trees just kept growing and did not stop to rest (and thereby develop a growth ring). In the 220 million years that have passed since this tree was alive and well, the entire North American continent, including all of the Chinle Formation, has migrated well north through the process now known as plate tectonics. If you value bulletproof provenance specimens coming out of old collections (like we do here at Mills Geological), this is a perfect fit for your collection.
2.75” x 1.75" on polished face; 1/4” thick slab $29
Chinle Formation, Triassic
Circle Cliffs, County, Utah
** Terrific genuine old-timer here. We recently acquired specimens out of an old collection on which the collector had noted the exact location and year that the piece was collected. Circle Cliffs petrified wood is distinctive for the rich reds and rust-reds that contrast strongly with the blacks, browns and whites. That’s why we love this small slice - it has exceptional presence and is made-to-order for the collector with limited space to store and display their collection. (And maybe we all fall into that category …?) The Araucariaceae Family dominated the Mesozoic Forests.
In the case of the Chinle Formation, the forest was located in the subtropical latitudes with a mild climate and year-round precipitation. That is the reason you see so few specimens with annual growth rings. Like the tropical and subtropical species today, those giant trees just kept growing and did not stop to rest (and thereby develop a growth ring). In the 220 million years that have passed since this tree was alive and well, the entire North American continent, including all of the Chinle Formation, has migrated well north through the process now known as plate tectonics. If you value bulletproof provenance specimens coming out of old collections (like we do here at Mills Geological), this is a perfect fit for your collection.
2.75” x 1.75" on polished face; 1/4” thick slab $29
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Ash (Fraxinus sp.)
Columbia Basalts Group, Miocene Yakima Canyon, Washington ** SPECTACULAR SLAB ALERT!! Slabs simply don't get much better than this unbelievably attractive specimen of Ash. If you value character and aesthetics, this specimen will be totally comfortable in the center position surrounded by all the rest of your best pieces. "Bulls eye" growth rings that we like to say you can see from across the room tell a story of wood anatomy as well as a promise of aesthetics. Those growth rings are color enhanced by the fact that ash is a ring porous wood with relatively large pores immediately in the spring wood which are followed in the summer wood by very small vessels in clusters or single. Those pores are considerably darker than the background tissue so the large ones make definition of the growth ring the darkest feature while the really small ones are somewhat eclipsed by the much lighter background tissue. Gosh, Jim just brought in a stick of wood from our woodpile for our wood stove - and it does not look as much like wood as this petrified one! Simply amazing detail that will be the first piece to catch the eye in your collection. Be sure to check out the photomicrograph showing the anatomical detail. Now – all that said – this great slab does have a repair at the 9 o’clock position. We always disclose that to buyers, but to be honest, this piece would be double the price if it were not for that repair before polishing. 8.25” x 6.5" on polished face; 1" thick slab $130 |
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Ash (Fraxinus sp.)
Grassy Mountain Formation; Middle Miocene Oregon-Idaho Graben unit 12.6-11.5 mbp Hoodoo Basin, Malheur County, near Vale, Oregon ** Hoodoo Basin produces some really great, unusual colors of mineralization. This lovely specimen is a prime example of yellow and blue! While not really "yellow," it is more like the color of various brands of prepared mustard. The blue even trends towards purple in some areas of the slab. Like a LOT of other colors in petrified wood, these colors are the result of traces of iron (and sometimes manganese) ions that have crept into the crystal matrix of silicon dioxide and occupy a position in the silicon dioxide tetrahedron that would normally be occupied by silicon. We are talking about parts per billion, not a massive invasion of iron or manganese but just enough to bend the light waves and thus turning the normally clear and colorless silicon dioxide into a more pleasing color. This specimen has just enough preserved wood anatomy to be able to identify it as being from an ash tree. It is a ring porous wood with distinct growth rings (which really show nicely in this specimen). Unlike other ring porous woods (Robinia, Gleditsia and Ulmus) also found at the Grassy Mountain sites, ash does not have vessel clusters in the summer wood - instead, it has individual vessels of similar but slightly smaller size than those in the spring wood. The Hoodoo Basin site is part of the Grassy Mountain area and will likely someday be turned into an open pit gold mine which is now in the planning/permitting stage by Paramount Gold Nevada Corp. Once development begins, it sadly will be the end of any more fossil wood from the site. 4” x 3” on polished face; slab 5/16" thick $67 |
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Primitive conifer (Araucariaceae Family)
Chinle Formation, Triassic
Hite, Utah
** Way up north, just about as far north that the Chinle Formation can be found, Hite is located on Lake Powell in southern Utah and is surrounded by very rugged country. Remarkably, it is related to the same members found in Arizona - the Petrified Forest Member and the slightly younger Owl Rock Member. This one is a fine example of the aesthetics that are possible when the dark black has contrasting areas of gray. The Araucariaceae Family dominated the Mesozoic Forests. In the case of the Chinle Formation, the forest was located in the subtropical latitudes with a mild climate and year-round precipitation. That's why you see so few specimens with annual growth rings. Like the tropical and subtropical species today, those giant trees just kept growing and did not stop to rest (and thereby develop a growth ring). This specimen shows a few "growth hesitations" likely caused by temporary climate changes such as lack of adequate precipitation or unusually low temperatures. In the 220 million years that have passed since this tree was alive and well, the entire North American continent, including all of the Chinle Formation, has migrated well north through the process now known as plate tectonics. It is wonderful to have a good story to go along with such an aesthetic specimen!
5” x 2.75” on polished face, 3/8" thick slab $45
Chinle Formation, Triassic
Hite, Utah
** Way up north, just about as far north that the Chinle Formation can be found, Hite is located on Lake Powell in southern Utah and is surrounded by very rugged country. Remarkably, it is related to the same members found in Arizona - the Petrified Forest Member and the slightly younger Owl Rock Member. This one is a fine example of the aesthetics that are possible when the dark black has contrasting areas of gray. The Araucariaceae Family dominated the Mesozoic Forests. In the case of the Chinle Formation, the forest was located in the subtropical latitudes with a mild climate and year-round precipitation. That's why you see so few specimens with annual growth rings. Like the tropical and subtropical species today, those giant trees just kept growing and did not stop to rest (and thereby develop a growth ring). This specimen shows a few "growth hesitations" likely caused by temporary climate changes such as lack of adequate precipitation or unusually low temperatures. In the 220 million years that have passed since this tree was alive and well, the entire North American continent, including all of the Chinle Formation, has migrated well north through the process now known as plate tectonics. It is wonderful to have a good story to go along with such an aesthetic specimen!
5” x 2.75” on polished face, 3/8" thick slab $45