Limb Cast

Object/Artifact

-

Crater Rock Museum

Name/Title

Limb Cast

Entry/Object ID

78.61.20

Description

Assemblage Zone: sedimentary Chemical Composition: Si O2 Crystal System: Hexagonal Description: Age: Mid-Miocene Location data: Crooked River Country, Near Prineville in Central Oregon, USA Description: Polished side shows a small crystalline hole surrounded by white fortification lines in a semitransparent light grey agate background. One side contains green minerals. Size: Diameter: 1 1/2" Length: (cast) 2 1/4" x 3 1/4" Type of Fossils Present: Plants Fracture: conchoidal Grain Size: Fine Hardness: 7 Quartz Lithofacies: Priineville Basalt 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

78.61

Source or Donor

Delmar Smith Limb Cast Collection

Acquisition Method

Donation

Other Names and Numbers

Other Number

Other Number: 1978.61.20

Dimensions

Dimension Notes

Dimensions taken at widest points

Location

Location

Container

Left

Drawer

2nd Shelf

Shelf

Right

Cabinet

Case #100

Wall

South wall

Building

Mentzer Hall - Petrified Wood Room

Category

Permanent