Limb Cast

Object/Artifact

-

Crater Rock Museum

Name/Title

Limb Cast

Entry/Object ID

05.58.206

Description

Chemical Composition: Si O2 Crystal System: Hexagonal Description: Family: Not Identified Age: Eocene to Oligocene Location data: Jackson County, Oregon, USA Roxy Fm. Description: Complete round limb cast, Brown, beige with white agate Type of Fossils Present: Plants Fracture: conchoidal Grain Size: Fine Hardness: 7 Quartz 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: Medium Rock Origin: Post-depositional Rock Type: Sedimentary Specific Gravity: 2.6 Surface Process: Not apparent Streak: white Temperature: Low Texture: Mircrocrystalline Variety: Petrified woods here are hydrous microcrystalline variety of quartz that can be generally termed as chalcedony.

Collection

Petrified Wood Collection

Acquisition

Accession

05.58

Source or Donor

Petrified Wood Collection

Acquisition Method

Donation

Other Names and Numbers

Other Number

Other Number: 2005.58.206

Dimensions

Width

6 in

Depth

4-1/2 in

Length

4 in

Dimension Notes

Dimension taken at widest points

Location

Location

Container

Right

Drawer

Bottom

Shelf

Left

Cabinet

Case #100

Wall

South wall

Building

Mentzer Hall - Petrified Wood Room

Category

Permanent