Quantitative Texture Analysis of an Anorthosite— Application to Thermal Expansion, Young′s Modulus and Thermal Stresses

Quantitative texture analysis of an anorthite (polycrystalline plagioclase feldspar) has been under taken using an optical microscope equipped with a universal stage. The microstructure was studied on three orthogonal sections. The microstructural shape analysis suggests an axial fabric which is confirmed by texture analysis. The texture has two major components, group I with ⊥(001) parallel to the axis of revolution and group II with ⊥(010). Group I has a much stronger axial character than group II. Using the orientation distribution function (ODF) defined by the individual orientations the thermal expansion, Young's Modulus and thermal stresses have been calculated for the plagioclase polycrystal. It is suggested that the distribution of thermal stresses could be used to estimate the orientation distribution of the poles to thermal cracks in the case of tensile (mode I) failure.