SYMPOSIA PAPER Published: 01 January 1966

The Role of Microstructure in the Physical Properties of Rock


The paper describes an approach to understanding rock properties through study of their relation to the microstructure of the rock. Petrofabric analyses of rock specimens, subjected to various physical property tests, have shown a strong correlation among several properties and some of the microstructural features. The equipment and techniques being used in these rock physics studies are discussed.

As an example of this work, the results of an experimental study of anisotropism in Salisbury granite are given. Oriented drill cores were cut in three mutually perpendicular directions from large blocks of the rock. Axial and diametric pulse velocity measurements were made on the cores to determine the direction and magnitude of elastic anisotropism. The cores were cut into disks and subjected to axial (point-load) and diametric (line-load) tension tests to determine direction and magnitude of strength anisotropism. The broken specimens were reconstructed, cut into thin sections, and examined petrographically. There was a strong correlation among the direction of maximum and minimum sonic velocity, preferred direction of failure, and a number of microstructural features, such as defect structures and grain orientation.

Author Information

McWilliams, J, R
Twin Cities Mining Research Center, Bureau of Mines, U.S. Department of Interior, Minneapolis, Minn.
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Developed by Committee: D18
Pages: 175–189
DOI: 10.1520/STP45141S
ISBN-EB: 978-0-8031-6016-3
ISBN-13: 978-0-8031-6170-2