Limb Cast

Object/Artifact

-

Crater Rock Museum

Name/Title

Limb Cast

Entry/Object ID

07.58.66

Description

Assemblage Zone: nonmarine volcanic sedime Chemical Composition: Si O2 Crystal System: Hexagonal Description: Common Name: Limb Cast Age: Late Eocene to Early Oligocene Location data: Dry Creek drainage, Jackson County, Oregon USA Description: A large limb cast of agate and jasper, very colorful: maroom, gold , black and white Size: 15.00"x 11.00"x 7.250" 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: Dark Rock Origin: Post-depositional Rock Type: Sedimentary Specific Gravity: 2.6 Surface Process: Not apparent Temperature: Low Texture: Microcrystalline Variety: Petrified woods ar hydrous microcrystalline varieties of quartz that can be generally termed as chalcedony or opalized .

Collection

Petrified Wood Collection

Acquisition

Accession

07.58

Source or Donor

Petrified Wood Collection

Acquisition Method

Donation

Other Names and Numbers

Other Number

Other Number: 2007.58.66

Dimensions

Width

11 in

Depth

7-1/4 in

Length

15 in

Dimension Notes

Dimension taken at widest points

Location

Location

Drawer

Right

Shelf

Bottom

Cabinet

Case #101(a)

Wall

South

Building

Mentzer Hall - Petrified Wood Room

Category

Permanent