Knowing the elastic properties of geo-materials is crucial to determine the mineralogical composition of the Earth's interior. The Brillouin scattering lab at the Helmholtz Centre Potsdam GFZ enables us to determine the velocities of sound waves in minerals, glasses and fluids to pressures of the deep Earth. We use Brillouin scattering - the inelastic scattering of laser light by thermal atomic vibrations (phonons) in the samples under investigation. We measure the frequency shift of the …