Earth Materials Laboratory, Department of Earth, Ocean and Atmospheric Sciences, Florida State University, Tallahassee, FL, 32306, USA.
GFZ, German Research Centre for Geosciences, 14473, Potsdam, Germany.
Sci Rep. 2018 Jan 22;8(1):1372. doi: 10.1038/s41598-017-17856-3.
Topaz is an aluminosilicate mineral phase stable in the hydrothermally altered pegmatitic rocks and also in subducted sedimentary lithologies. In nature, topaz often exhibits solid solution between fluorine and hydrous end members. We investigated elasticity of naturally occurring single crystal topaz (AlSiOF(OH)) using Resonant Ultrasound Spectroscopy. We also explored the temperature dependence of the full elastic constant tensor. We find that among the various minerals stable in the AlO-SiO-HO ternary system, topaz exhibits moderate elastic anisotropy. As a function of temperature, the sound velocity of topaz decreases with [Formula: see text] and [Formula: see text] being -3.10 and -2.30 × 10 km/s/K. The elasticity and sound velocity of topaz also vary as a function of OH and F content. The effect of composition ([Formula: see text]) on the velocity is equally important as that of the effect of temperature. We also note that the Debye temperature ([Formula: see text]) of topaz at room temperature condition is 910 K and decreases at higher temperature. The Debye temperature shows positive correlation with density of the mineral phases in the AlO-SiO-HO ternary system.
黄玉是一种在热液蚀变的伟晶岩和俯冲沉积岩中稳定存在的铝硅酸盐矿物相。在自然界中，黄玉通常表现出氟和含水端元之间的固溶体。我们使用共振超声光谱法研究了天然单晶黄玉（AlSiOF(OH)）的弹性。我们还探讨了全弹性常数张量的温度依赖性。我们发现，在 AlO-SiO-HO 三元体系中稳定存在的各种矿物中，黄玉表现出中等的弹性各向异性。随着温度的升高，黄玉的声速随[Formula: see text]和[Formula: see text]的降低而降低，分别为-3.10 和-2.30×10 km/s/K。黄玉的弹性和声速也随 OH 和 F 含量而变化。组成([Formula: see text])对速度的影响与温度的影响同样重要。我们还注意到，黄玉在室温条件下的德拜温度([Formula: see text])为 910 K，在较高温度下降低。德拜温度与 AlO-SiO-HO 三元体系中矿物相的密度呈正相关。
