We present here the latest results from experimental studies aiming at measuring the Mass
Absorption Coefficient (MAC) of interstellar silicate dust analogues at low temperatures
in the far infrared and submillimetre domains which are necessary for the analysis of
astronomical data. These results show that above 100 μm, the MAC of
amorphous silicate nano-grains has a complex dependence with the grain temperature and
with the wavelength. This has to be considered when interpreting astronomical observations
to avoid errors on the derived parameters such as the dust mass and its physical and
chemical properties.