Abstract
Polycrystalline aggregates of SnO 2-cassiterite and GeO 2-rutile have been hot-pressed in a piston-cylinder apparatus at P = 30 kbar and T ⩽ 1,000°C. These specimens are less than 2% porous and less than 20μ in grain size. Compressional ( V p) and shear ( V s) velocities are determined as a function of pressure to 7.5 kbar at 293 K by the ultrasonic-pulse superposition method. Extrapolation of the velocity—pressure data to P = 1 ba yields the following velocities (units: km/sec) for the compressed polycrystalline aggregate SnO 2: V p = 6.91, V s = 3.75; for GeO 2: V p = 8.56, V s = 4.83. Comparison with published data for single-crystal GeO 2 indicates that our specimen is elastically isotrop within 1%. The bulk sound velocities ( V φ ) for the rutile minerals SiO 2, GeO 2 and SnO 2 are systematically related to density, with TiO 2 being anomalous. Shankland's (1972) equation (∂ ln V φ ∂ ln M) x = − 1 2 (where M is mean atomic weight) represents these rutile data well.
Published Version
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