Basic mold material that mainly consists of (Mg, Fe)2SiO4.
It is characterized by its olive-green, white-green or brown-yellow color and has an irregular, splintery grain structure. Due to its high-alkaline characteristics, olivine sands cannot be hardened with acidic cold-setting resin (see Cold setting process). It features relatively high fire resistance, even expansion under temperature, high thermal conductivity (3-4 W/mK in solid state in contrast to quartz sand with 1.4 W/mK in solid state), low risk of slagging and no risk of silicosis.
Respectively, it was discovered at samples from molds with quartz and olivine sand as well as the Al Si12CuNiMg alloy that the dendrite arm spacing has considerably improved due to the better thermal conductivity of olivine sand leading to improved mechanical properties (Figures 1 and 2).
As a result of the uneven grain distribution (see Sand grain), olivine sand has a lower permeability to gas than, for example, quartz sand.