Our  Featured  Specimen

Updated 5/14/2012

WELCOME TO MILLS GEOLOGICAL

specializing in unusual, identified petrified wood

and plant fossils from around the world

We invite you to click on any photo to see a larger, more defined photo of the select specimen. For a more complete listing of our specimens, please download our catalog from from the links below.

Thanks for your continued loyalty!

Jim and Beth

Root Cast Mass in Matrix

San Miguel County, Colorado

**  Fascinating specimen of rather long rootlets massed in a welded-tuff matrix.  All of these rootlets are agatized casts and therefore do not have sufficient structure to determine taxonomic affinity, but they do offer an intriguing view of rootlets that must have been exposed to the air when they were covered by very hot volcanic ash and debris.  Be sure to click photo for a closer view.

4" x 3" root mass; 1.5" thick. 

Individual rootlets vary in diameter from 1/4" to 1/2"   $42

Cherry (Prunus sp.)

Bretz Mine Airport Site, McDermitt Nevada/Oregon

** Ahhh...we just love these main limbs with a separate branch coming out at the side! This Cherry has an exquisite second center at the 9:00 position where the branch is leaving the main limb.  The Bretz Mine was a Mercury mine in the mid-19th century and the airport was a gravel strip to enable executives and specialized technicians to fly into this remote part of northern Nevada and southern Oregon.  These days, only rockhounds and hunters visit the area and the airport is barely visible but the name persists as a locality reference for diggings (some of which go down 14 feet) of fine petrified wood specimens.  Another interesting fact: the site is actually related to a giant volcanic caldera that was active during Miocene times (Trout Creek Formation) and which produced the mercury that was mined as well as the wood that is still collected. 

7" x 4.5" on polished face; 1/2" thick slab    $47

Blue-green Algae Stromatolites 

(Collenia undosa)

Biwabic Iron Formation;  Lower Chert Member

Precambrian 2.2 billion years old

Biwabic, Mesabi Range, Minnesota

**  At 2.2 billion years old, this is definitely the oldest stromatolite to have been found in the US, but perhaps not the oldest on record worldwide.  Once called by the common name "Blue-Green Algae," the Collenia genus is now classed as a Cyanobacteria.  It is theorized that these early Precambrian organisms were responsible for the release of oxygen from rocks that now makes up the important (to us) part of our atmosphere.  The Collenia are characterized as turbinate growths.  Their life was frequently interrupted by the settling out of silt or precipitation of limestone which covered the growing surface.  The organism would respond by breaking through the silt and then covering it with another complete growing surface.  This is what gives these stromatolites their layered appearance.

7" x 3.5" on polished face; 1/4"  thick slab  $48

Sycamore  (Platanus sp.) Limb end cut

Clarno Formation, Middle to Late Eocene

Hampton Butte, Oregon

** Beautiful olive green mineralization and a hint of pale blue agate make this end cut of sycamore special.  This is a petrified limb with a good ray pattern and just enough preservation to identify it as sycamore.  The back of this end cut is weathered out, but that helps it stand at a 45-degree angle for display. 

2.5" diameter on polished face; 1" to 2.5" long end cut    $29

Camphor wood  (Cinnamomum sp.)

Mehama Volcanics, Little Butte Formation, Oligocene

Calapooia River near Sweet Home, Linn County, Oregon

**  This camphor wood has really outstanding preservation of fine wood structure.  The vessels are clear and distinct throughout the specimen and growth rings are absolutely well defined when viewed under magnification.  This tree underwent periodic years of drought when only one or two vessels were produced for several years in a row.  Then when rains returned, the tree responded by putting on substantially more growth each year.  You can see an example of this cycle on the photomicrograph to the right.  This slab is cut the old fashioned way - an inch thick - the way they used to do it when petrified wood was thought to be inexhaustible!

6.5" x 5.5" on polished face; 1" thick slab   $68

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