Limb Cast

Object/Artifact

-

Crater Rock Museum

Name/Title

Limb Cast

Entry/Object ID

06.58.28

Description

From Heart Mountain Chemical Composition: Si O2 Crystal System: Hexagonal Description: Family: Not Identified Common Name: Opalized Limb Cast Age: Unknown Location data: Unknown Description: Very large opalized limb cast, outer side bark like in beigish-tan, inner side show a mustard yellow opalization 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: Light 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

06.58

Source or Donor

Petrified Wood Collection

Acquisition Method

Donation

Other Names and Numbers

Other Number

Other Number: 2006.58.28

Dimensions

Width

14 in

Depth

9-1/4 in

Length

22 in

Dimension Notes

Dimension taken at widest points

Location

Location

Shelf

Bottom

Cabinet

Case #100(a)

Wall

South

Building

Mentzer Hall - Petrified Wood Room - Case #100

Category

Permanent