4/22/24
The local rock and gem show in San Luis Obispo County took place this past weekend, and Jim displayed a case of Mesozoic fossil Araucaria wood, explaining their spread through Pangaea. ------ We appreciate your business and your friendship. Jim Mills and Beth Myers |
Welcome to Mills Geological quality identified petrified wood and plant fossils from around the globe |
Our featured specimen
Black Locust encased in algae (Robinia zirkelii)
Miocene, Trout Creek Formation
Diggings near McDermitt, Nevada/Oregon border
** McDermitt has produced fossil wood in algae from three different sites where the specimens have been preserved in three distinct colors - a different color of the fossil algae at each site. We suspect the differences are the result of different volcanic events over the span of Trout Creek time. All of the geological evidence points to there being numerous eruptions separated by longer periods of quiescence in between eruptions. Color differences are most likely caused by complex differences of the geochemistry of the ash along with different chemical characteristics of the groundwater which began to weather the volcanic ash to provide the silica for permineralization. The result - brown, yellow and green coloration in the fossil algae. This specimen is from the brown algae site - the one with the best preservation of the stromatolitic algae colonies but with wood preservation nearly approaching unidentifiable. The algae appear to have had more time to form and grow at the brown algae site giving the fungal and bacterial agents more time to attack and destroy wood tissue. Hydrolization by the water also added to the disintegration of the wood tissue. Fortunately, there is just enough remaining anatomy preserved to get a good identification on this particular stem. It is a Black Locust. The Latin name Robinia zirkelii is applied to all fossil Robinia in North America. The color changes reflect the differences between iron oxides with different valences of the iron ion in the compound. We love having all three sites represented in our own collection so they can be displayed beside one another to help illustrate the story of volcanic activity during Trout Creek time. We have reason to believe that all three sites are now completely depleted so this is a rare opportunity to add a brown algae site slab to your collection if it is currently missing.
5.75” x 4.25” on polished face; end cut varies from 3/8” to 1.5” thick $80
Miocene, Trout Creek Formation
Diggings near McDermitt, Nevada/Oregon border
** McDermitt has produced fossil wood in algae from three different sites where the specimens have been preserved in three distinct colors - a different color of the fossil algae at each site. We suspect the differences are the result of different volcanic events over the span of Trout Creek time. All of the geological evidence points to there being numerous eruptions separated by longer periods of quiescence in between eruptions. Color differences are most likely caused by complex differences of the geochemistry of the ash along with different chemical characteristics of the groundwater which began to weather the volcanic ash to provide the silica for permineralization. The result - brown, yellow and green coloration in the fossil algae. This specimen is from the brown algae site - the one with the best preservation of the stromatolitic algae colonies but with wood preservation nearly approaching unidentifiable. The algae appear to have had more time to form and grow at the brown algae site giving the fungal and bacterial agents more time to attack and destroy wood tissue. Hydrolization by the water also added to the disintegration of the wood tissue. Fortunately, there is just enough remaining anatomy preserved to get a good identification on this particular stem. It is a Black Locust. The Latin name Robinia zirkelii is applied to all fossil Robinia in North America. The color changes reflect the differences between iron oxides with different valences of the iron ion in the compound. We love having all three sites represented in our own collection so they can be displayed beside one another to help illustrate the story of volcanic activity during Trout Creek time. We have reason to believe that all three sites are now completely depleted so this is a rare opportunity to add a brown algae site slab to your collection if it is currently missing.
5.75” x 4.25” on polished face; end cut varies from 3/8” to 1.5” thick $80
Dicot wood (Caesalpinoidea subfamily) Yegua Formation Eocene Apple Springs area, Houston & Trinity Counties, Texas ** An unusual (and oh by the way beautiful) fine display slab with a clearly-marked center pith that makes it easy for the observer to identify it as fossil wood. 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 very large size of the vessels. Indeed, they are well into the 200+ micron range of diameter and there are a lot of them! An oddity of statistics is that their very large size 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. Until only recently, the Caesalpinoideae were assigned to the Leguminosae family but they have now been assigned to the Fabaceae family. Yes, in botany, the taxons sometimes seem to move about as the science gets more technical. The aesthetics of this specimen alone make it a desirable addition to collections of fine fossil wood. Pronounced radial patterns created by leaching along desiccation cracks and a range of tan and brown hues make for very pleasing patterns. In sum - we like it! Advance your collection with this nice identified specimen. 8.5” x 6.5” on polished face; 3/4” thick slab $90 |
"Haw" or "Linden" tree (Viburnum sp.)
Mehama Volcanics Unit, Little Butte Formation, Oligocene Sweet Home area, Oregon ** 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 according to your own location! While much of the Sweet Home wood's preservation of anatomy can be hard to find, this one does have visible structure throughout the slab along with those well-defined annual growth rings. The first thing that you should notice is the angular character of most vessels. And note the vessels are almost entirely singular and their density is well within the range of 40 to 100 per square millimeter. 5.5" x 4" on polished face; 5/16" thick slab $48 |
Schilderia
Chinle Formation, Triassic
old Paulsell Ranch, Navajo/Apache Counties, Arizona
** The striking feature of this nice Schilderia is the definition of the radial grain, which is a distinguishing feature of Triassic Schilderia. The genus Schilderia is a very scarce fossil wood in the Chinle Formation, accounting for less than 2% of the total amount of wood from the region. Its taxonomy has been an enigma over the years but most paleobotanists now agree that it should be assigned to the Family of Gnetales. Oddly, one of the only living members of this family in the Southwest region these days is a desert shrub in the genus Ephedra which is usually referred to by its common name of “Mormon Tea.” It has been found in different small deposits of the region but always as a minor constituent of the deposit accompanying the more common Araucarioxylon and Woodworthia. This is a handsome example of an unusual Chinle genus. The 60,000 acre Paulsell Ranch was adjacent to the east boundary of Petrified Forest National Park and acquisition of the ranch by the Park Service was authorized in 2004. Specimens from the old Paulsell Ranch are now no longer available for collecting so if your collection is enhanced by rare species from closed localities - this is a great addition.
6” x 4.5" on polished face; end cut varies in thickness from 1.75” to 1” $58
Chinle Formation, Triassic
old Paulsell Ranch, Navajo/Apache Counties, Arizona
** The striking feature of this nice Schilderia is the definition of the radial grain, which is a distinguishing feature of Triassic Schilderia. The genus Schilderia is a very scarce fossil wood in the Chinle Formation, accounting for less than 2% of the total amount of wood from the region. Its taxonomy has been an enigma over the years but most paleobotanists now agree that it should be assigned to the Family of Gnetales. Oddly, one of the only living members of this family in the Southwest region these days is a desert shrub in the genus Ephedra which is usually referred to by its common name of “Mormon Tea.” It has been found in different small deposits of the region but always as a minor constituent of the deposit accompanying the more common Araucarioxylon and Woodworthia. This is a handsome example of an unusual Chinle genus. The 60,000 acre Paulsell Ranch was adjacent to the east boundary of Petrified Forest National Park and acquisition of the ranch by the Park Service was authorized in 2004. Specimens from the old Paulsell Ranch are now no longer available for collecting so if your collection is enhanced by rare species from closed localities - this is a great addition.
6” x 4.5" on polished face; end cut varies in thickness from 1.75” to 1” $58