MILLS GEOLOGICAL

Our featured specimen

Maple Nurse Log with penetrating rootlets (Acer sp. & Incertae sedis)
Little Butte Formation, Mehama Volcanics; Oligocene
Sweet Home Petrified Forest, Linn County, Oregon
** Take a close look at this really interesting nurse log. This maple log was dead, down and beginning to rot in the forest duff when it served as a nurse log for other plants. See our photomicrographs to see how these new growths began to penetrate the rotting log which likely retained plenty of moisture for germination and sprouting. There is only a small portion of the slab that has good preservation of the Acer sp. - a testament to the rotting nature of the log. There are numerous very small rootlets that have begun to grow in the more digested portions of the log. We love these specimens with a story to tell. The culmination of this story begins with the volcanic eruption that must have covered the log killing all of the plants it hosted. A coating of volcanic ash surrounding the slab verifies the final result - preservation via permineralization. It was then simply a matter of (a long) time waiting until a rockhound dug up the log and turned it into a collectible specimen. Fantastic specimen for those of us who love to advance our knowledge and our collections.
7” x 6” on polished face; 5/8” thick slab $89

Vesselless Dicot
Trout Creek Formation, Miocene
Zimmerman Ranch at the McDermitt diggings, Oregon/Nevada
** Quite scarce - very unusual - and attractive as well! You immediately know that something is different because there are wide medullary rays (much wider than any conifer) but not a vessel in sight. There are only three families of angiosperm dicot trees that produce wood with absolutely no vessels. They are Trochodendraceae, Tetracentraceae, and Winteraceae. This fossil wood is a new species in one of those families. All other angiosperms produce wood with vessels. The only other vesselless angiosperm wood described in the fossil wood record is Trochodendron beckii from the Sweet Home, Oregon area. The pale red exterior on this nice 1.75" long piece makes it a great display specimen.
Click the photomicrograph above to see closer views of the polished face and structure.
1.75" x 1" on polished face; 2" long limb section $49

Black Locust (Robinia sp.)
Trout Creek Formation, Miocene
McDermitt, Nevada/Oregon
** An outstanding slab of Black Locust (Robinia sp.) with excellent woody fine structure -- see photomicrograph. The McDermitt area has several diggings locations within a 15 to 20 mile radius. This piece from the Bretz 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." This is an excellent slab from the area!
7" x 5.5" on polished face, 7/16" thick slab $70

Yew (Taxus sp.) in Stromatolitic Algae
"Tonopah Wood"
Miocene
Tonopah, Nevada
** An exceptionally beautiful example of “Tonopah Wood” with fabulous color and patterning of the algae! Old-timer rockhounds gave these attractive specimens the name "Tonopah" after the nearby old mining town of the same name in Nevada. The wood was under water and encased in stromatolitic algae prior to the volcanic event that filled the water body with ash and began the petrification process. The mineralization of the algae in this specimen has the very desirable salmon pink coloration. The wood itself is at the center of the slice. Much of it has been macerated and broken apart but enough anatomical structure remains to determine that it was a Yew (Taxus sp.). Maceration makes considerable sense because the wood must have been under water for quite some to enable the growing stromatolitic algae to completely encapsulate the wood. As a result, the specimens from Tonopah are generally valued more for their aesthetic appeal than for their wood anatomy. If you are also an algae enthusiast, the differentiation of mineralization (color) and form (some colonies small, some larger) make this an even more interesting specimen.
3.25" x 2.5" on polished face; 3/16" thick slab $40

Limb cast (Incertae sedis)
Andesite and Basaltic overlapping flows Middle Miocene
Brogan, Oregon
** Incredible color with a really gnarly exterior. That pretty much sums up what we love to find in a limb cast and this specimen has it in "spades." The lovely light to dark purple color and the contrasting white rind make this a specimen with eyecatching appeal. The gnarled woodgrain character of the exterior makes this piece obviously petrified wood for any novice observer. Check out these knots (shown right) on the outside! It displays perfectly sitting on its natural uncut end (upper right picture). If you like limb casts, don't let this one get away because it is perfect for your display case.
3" x 2" on polished face; 3" Height varies from 1.25" to 3" tall $49

Conifer (Pinales Order)
Miocene Rhyolitic Flow
Badger Flat, near Vya, Nevada
** An end cut with a beautiful polished face and a very nice woody character along the exterior length. It will display very nicely just sitting on its natural bottom side. Click on the photo to see the excellent definition of very tight growth rings. The tight growth rings suggest that the tree was growing on a marginal piece of habitat. A fine addition to any collection.
1.75" x 1.5” on the polished face; 3" maximum thickness $30

Teredo bored driftwood (Incertae sedis)
Saltos Shale Member, Monterey formation Middle Miocene
Santa Barbara Canyon, near Cuyama, California
** Here's a very handsome slab of petrified wood with multiple borings from teredos. The Saltos Shale is mostly marine strata that intertongues with the Lower Miocene mixed marine and terrestrial, Vaqueros Formation. We have offered Vaqueros wood in our inventory in the past and it (of course being terrestrial) never has any teredo tunneling. On the other hand, the Vaqueros wood usually has well-preserved wood structure. In contrast, the Saltos Shale wood does not have preservation of wood anatomy but the fact that it is severely bored by teredos is a good indication that wood in this strata must have floated into an embayment with flood waters and spent considerable time in the water, providing a happy home for the so-called teredo worms. Some of the (quite large) borings are filled with mudstone and some are hollow. Many of them are lined with a thin veneer of chalcedony and a few of them have tiny quartz crystals lining the cavity. The so-called teredo worms are not worms at all; they are gastropods. Their shells have become extremely diminished to the point that they live entirely outside of their shell (in their tunnels), opening and closing the now very tiny bivalve shell to literally gnaw their way through the waterlogged, and thus softened wood. In the early days of seafaring before the invention of iron boats (or the replacement of wooden pleasure craft with fiberglass hulls) the teredos were much hated by sailors who were forced to pull their ships out of water frequently to scrape off the critters before they bored tunnels through the wooden hulls. I've always been amazed that the individual teredos are able to avoid crossing any other individual's track. They almost always exhibit parallel travel patterns as is the case in this specimen where all of the borings are parallel to the axis of the tree. Scientific and decorative!
7" x 5" on polished face; 5/8" thick slab $42