• journal_title：American Mineralogist
• Contributor：Zhu Mao ; Fuming Jiang ; Thomas S. Duffy
• Publisher：Mineralogical Society of America
• Date：2007-
• Format：text/html
• Language：en
• Identifier：10.2138/am.2007.2329
• journal_abbrev：American Mineralogist
• issn：0003-004X
• volume：92
• issue：4
• firstpage：570
• section：Articles

The single-crystal elastic constants of zoisite Ca₂Al₃Si₃O₁₂(OH) were determined by Brillouin scattering at ambient conditions. The elastic tensor was obtained by an inversion of acoustic velocity data for three different crystal planes. The aggregate bulk modulus, shear modulus, and Poisson’s ratio are K_S0 = 125.3(4) GPa, G₀ = 72.9(2) GPa, and σ₀ = 0.26(1) for the VRH (Voigt-Reuss-Hill) average, respectively. The maximum azimuthal anisotropy of zoisite is 22% for compressional velocity and 33% for shear velocity. The maximum shear splitting is 21% along the [001] direction. Our results resolve the discrepancies in bulk modulus and axial compressibilities reported from static compression studies, and provide the first experimental constraints on the shear modulus. Trends in the elastic moduli of minerals in the CaO-Al₂O₃-SiO₂-H₂O (CASH) system are evaluated.