magnesium silicate

noun Chemistry.

1. a white powder, 3MgSiO3⋅5H2O, with variable hydration, insoluble in water or alcohol, used as a rubber filler, a bleaching agent, an odor absorbent, and in the manufacture of paints and resins.
2. any silicate containing magnesium, as enstatite, talc, or magnesium trisilicate.