Someone is pulling your leg. Beryllium is not a liquid at ordinary temperatures - it certainly doesn't have a characteristic viscosity that can be measured in any of the conventional ways. Beryllium is a steel gray and hard metal that is brittle at room temperature and has a close-packed hexagonal crystal structure. It has exceptional flexural rigidity (Young's modulus 287 GPa) and a reasonably high melting point. The modulus of elasticity of beryllium is approximately 50% greater than that of steel. The combination of this modulus and a relatively low density results in an unusually fast sound conduction speed in beryllium. But viscous, it ain't!!!