Abstract
Amber is a unique biopreservation organic material in which ancient insects, animals, and plants were
fossilized for a few tens of millions of years. The pressure-dependence of the elastic properties of the Baltic
amber was studied using a micro-Brillouin scattering system and a diamond anvil cell up to 12 GPa. As the
pressure increases, the sound velocity of longitudinal acoustic (LA) wave rapidly increased in the
low-pressure regime and became gradual increase at high-pressures. The pressure dependence of the LA
velocity is discussed based on the excess vibrational density of states of a glass.
