Structural geologists are well aware of the fact that isotropic rocks are quite exceptional in nature. Whicheverorigin, sedimentary, metamorphicormagmatic, rocks are shaped with a plane of mineral flattening, the foliation in geologists' jargon, and with a line ofmineral elongation, the lineation. Just like a good quarryman, a trained structural geologistwill detectapreferredorientationin an apparently isotropic granite. Preferred mineral orientation and thus structural anisotropy are the rule in nature. Consideringthe largevariationsinelasticcoefficientsofrock-forming minerals, itcould be...

Structural geologists are well aware of the fact that isotropic rocks are quite exceptional in nature. Whicheverorigin, sedimentary,metamorphicormagmatic, rocks are shaped with a plane of mineral flattening, the foliation in geologists' jargon, and with a line ofmineral elongation, the lineation. Just like a good quarryman, a trained structural geologistwill detectapreferredorientationin an apparently isotropic granite. Preferred mineral orientation and thus structural anisotropy are the rule in nature. Consideringthe largevariationsinelasticcoefficientsofrock-forming minerals,itcould be...