Limb Cast

Object/Artifact

-

Crater Rock Museum

Name/Title

Limb Cast

Entry/Object ID

78.61.35

Description

Limb Cast Eocene Clarno Formation Crooked River, Crook Co., OR Assemblage Zone: tropical to subtropical Chemical Composition: Si O2 Crystal System: Hexagonal Description: Age: Eocene Location data: Clarno Formation, Hampton Butte, Central Oregon USA Description: Delmar said this was his largest limbcast, where a hole log was replaced by agate rather than a limb a slab of this log is on display. The polished face show half of the piesc is fortified agate in shades of grey and white (center contains eye), off center is a triangular white fortified area with numerous cracks in the surface area . The rest of the rock is in shades of green & brown opaque rock, there is an open rectangular shape slit in this area. Size: Diameter: 16 1/2" Length: 1 3/4" Type of Fossils Present: Plants Fracture: conchoidal Grain Size: Fine Hardness: 7 Quartz Lithofacies: volcaniclastic Luster: Glassy Occurrence: Like petrified wood, limb cast are created in much the same manner. Volcanic ash or silica-rich sediment buries a tree limb, the limb decays, leaving behind an open void. This void works as a mold that fills with amorphous silica that has percolated through the surrounding rock. Once microamorphous silica has filled the mold and the crystallization process to a (quartz)chalcedony or opal is complete, the result is a siliceous rock with the same exterior markings as the original limb. Pressure: Low-Moderate Rock Color: Light Rock Origin: Post-depositional Rock Type: Sedimentary Specific Gravity: 2.6 Surface Process: Not apparent Streak: white Temperature: Low Texture: Microcrystalline Variety: Petrified woods here are hydrous microcrystalline variety of quartz that can be generally termed as chalcedony or opal.

Collection

Petrified Wood Collection

Acquisition

Accession

78.61

Source or Donor

Delmar Smith Limb Cast Collection

Acquisition Method

Donation

Other Names and Numbers

Other Number

Other Number: 1978.61.35

Dimensions

Dimension Notes

Dimension taken at widest points.

Location

Location

Container

Left

Drawer

Bottom

Shelf

Right, Right

Wall

Right

Building

Mentzer Hall - Petrified Wood Room

Category

Permanent

Moved By

Catherine Boyd

Date

March 6, 2008

Location

Container

Left

Drawer

Bottom

Shelf

Right

Cabinet

Case #100

Wall

South wall

Building

Mentzer Hall - Petrified Wood Room

Category

Permanent