Thermal expansion of tourmaline single crystals from 80 to 300 K

The thermal expansion and coefficient of linear thermal expansion of elbaite, schorl, and uvite specimens in the a and c directions have been determined from 80 K to room temperature with use of the standard strain-gauge technique. At room temperature it was found that for elbaite, ${\alpha }_a$=3.86×${10}^{\mathrm{-}6}$ ${\mathrm{K}}^{\mathrm{-}1}$ and ${\alpha }_c$=9.11×${10}^{\mathrm{-}6}$ ${\mathrm{K}}^{\mathrm{-}1}$; for schorl, ${\alpha }_a$=3.48×${10}^{\mathrm{-}6}$ ${\mathrm{K}}^{\mathrm{-}1}$ and ${\alpha }_c$=8.54×${10}^{\mathrm{-}6}$ ${\mathrm{K}}^{\mathrm{-}1}$; and for uvite, ${\alpha }_a$=3.17×${10}^{\mathrm{-}6}$ ${\mathrm{K}}^{\mathrm{-}1}$ and ${\alpha }_c$=8.32×${10}^{\mathrm{-}6}$ ${\mathrm{K}}^{\mathrm{-}1}$. It was observed that the anisotropy in thermal expansion along the a and c directions of tourmalines is directly related to the anisotropy in the corresponding adiabatic elastic constants.