Microstructural techniques in the study of physical properties of rock

Petrography and Physicomechanical Properties of Rocks from the Ambela Granitic Complex, NW Pakistan

“…The generally agreed upon geotechnically important features of rocks include (i) modal mineralogical composition, (ii) grain size and extent of its variation, (iii) grain shape, (iv) the overall abundance of flaky minerals (mica) and, more importantly, the degree of their preferred orientation, and (v) degree of weathering or alteration [8, 12, 14, 17–21]. Rocks containing large amounts of physically competent minerals are obviously strong.…”

The engineering petrography of a weathered granite in Cornwall, England

“…Attempts have been made to quantify microfractures in relation to certain measured elastic properties of fresh rocks (McWilliams 1966, Willard & McWilliams 1969. More recently Simmons et al (1975) have emphasised that in studying cracks in rocks, values are needed for such parameters as crack dimensions, number of cracks per unit area or volume and the distribution and orientation of cracks.…”

Deformations associated with relaxation of residual stresses in a sample of Barre Granite from Vermont

“…In addition, the quartz optic axer are strongly oriented nearly parallel to the rift plane. Willard and McWilliams (1969) found a similar strong concentration of microfractures parallel to the plane of easiest tensile fracture (the rift plane).…”

“…Douglass and Voight (1969) found microfractures and fluid inclusions (healed microfractures) to bs strongly oriented parallel to the rift plane, which is vertical and strikes about N. 80° E. They found a smaller concentration of microfractures in the grain direction parallel to the horizontal lift plane, but where the quartz optic axes are strongly oriented parallel to the rift plane, they related these features to the laboratory-determined compliance ellipsoid. Willard and McWilliams (1969) found a similar strong concentration of fractures parallel to the plane of easiest tensile fracture, which is most likely the rift plane. Bur, Hjelmstad, and Thill (1969) Friedman, oral commun., 1971).…”