  Dust is formed in the expanding atmosphere during late stages of stellar
evolution. Dust influences the dynamics and thermodynamics of the stellar
atmosphere by its opacity. The dust opacity depends both on the optical
properties of the grain material as well as on the amount of dust present. A
rich source of information on some mineral phases of dust in AGB stars comes
from the study of presolar grains from meteorites. This paper presents a short
overview of presolar grains studies and describes how the optical properties of
dust grains are obtained in the laboratory.
