Absorption efficiency Q_λ for a composite material of forsterite and metallic iron with varying volume fractions of iron from 0 to 60% in steps of 5%. The redline corresponds to pure forsterite, the green line to a volume fraction of iron of 35% at the border between insulator-like and metal-like absorption behaviour, and the blue line corresponds to pure iron. For clarity, successive lines are vertically shifted by a factor of two with respect to each other.