MILLS GEOLOGICAL

Our featured specimen

Primitive Whitethorn (Ceanothus sp.)
Tertiary
Chimney Creek, Nevada
** This very interesting shrub section was a precursor to the modern plants called Mountain Whitethorn or sometimes Snowbush. Check out the photomicrograph to see wood structure that is semi-ring-porous with vessels in the range of 50 microns. This hardy shrub did not require a lot of water in the summer and that is reflected in the sparseness of vessels following the spring mass of vessels. Like many shrubs, the individual "trunks" are ramrod straight as in this specimen. We are told by the seller that it was from a new find a bit to the north of Chimney Creek and was recovered during the 2021 season. Definitely something different!
6” x 3.5” on the polished face, 7/16” thick slab $40

Palm roots (Rhizopalmoxylon)
Kern River Formation, Miocene
Edison, Kern County, California
** We really love these Edison specimens with nearly all of the palm roots outlined with a thin black line. That highlight makes the roots almost pop out of the slab. The Edison locality is at the mouth of the Kern River Canyon – all of it is river outfall alluvial deposits. Knowledgeable field collectors always look for the first hint that workers in the extensive citrus groves in the area will be plowing firebreaks between the roadside and their groves because those plows often bring nice cutting size cobbles of palm roots. Those cobbles have been transported down from strata now completely eroded and gone but it is believed that they are Miocene in age.
7” x 5” on polished face; 1/4” thick slab $79

Yew (Taxus sp.) in Stromatolitic Algae
"Tonopah Wood"
Miocene
near Tonopah, Nevada
** A stunning example of “Tonopah Wood” with incredible patterning! Old-timer rockhounds called these attractive specimens by that name. 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 bronze coloration. The wood itself, was the center of the polished face. Much of it has been macerated and no longer can be recognized as wood. The light brown wood still retains the characteristics we look for in petrified wood. Like almost all of the specimens we have ever seen from this locality, there is enough tracheid remnant to determine that it was a Yew (Taxus sp.). The wood must have been under water for a long time for colonies of stromatolitic algae to grow. 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 wide bands and some very narrow) make this an even more interesting specimen. The implication of these differences is that there were some substantial changes in the water chemistry and habitat during the growth of the algae over time. A delicious mystery in a very handsome piece!
7" x 6" on polished face; 5/16" thick slab $59

Laurel (Laurinoxylon sp.)
Laney Shale Member, Green River Formation, Eocene
Eden Valley, Wyoming
** Here's a striking classic slab in black and Blue Forest gray blue. Those dessication cracks filled with blue agate are key indicators that this was a dead and down limb of wood. It had begun to crack along medullary rays all the way from the periphery to the center. That center is filled with particles of sand indicating that it may well have been in an environment with some flowing water during flood events bringing in fresh sediments. A fascinating story that can be told about the specimen. The Lauraceae family is exceptionally large with 45 genera and over 2000 species and those are just the ones living in the world today! The wood anatomy of the laurels tends to be very similar among all of the genera and species and as a result, paleobotanists have erected the form genera Laurinoxylon for woods which share the characteristics of wood anatomy with the family, but which cannot be assigned to one of the many existing genera based only upon the wood anatomy. (Note the plume of blue gray agate that seems to be growing like a flower pistil from the white center.)
5.75” x 5” on the polished face; 1/2" thick slab $45

Willow (Salix sp.)
Ash of the Juniper Mountain Volcanic Center Miocene
Coyote Grade, Shares Basin, Owyhee County, Idaho
** This is an extra-special wood specimen from a new "old" locality for us. This specimen was collected in some of the ash beds east of Highway 95, south of Marsing, Idaho in the 1950s by the brother-in-law of one of our favorite petrified wood cutters/dealers. We were fortunate to be able to purchase a few of the specimens this person collected nearly three-quarters of a century ago. The piece is distinctive - a covering of white volcanic ash on the fossil wood, with a ropey looks that invokes a water-worn appearance. This indicates that it weathered out of the ash and lay in a riverbed for quite some time prior to being found. We searched the Internet for more information about the location, but found only a few references to collecting small chips of wood and agate in some of the area's streambeds. There are quite a few outcrops of volcanic ash in this part of Owyhee County and one of them produced this beautiful specimen all those years ago! This is not a full round limb section, but a lath off of a larger limb or trunk. Gorgeous polished face! Ideal contrast between face and exterior. A beauty.
3" x 1.5" on polished face; lath section 10" in length $125