H₂O molecules attracted to internal or external surfaces of a phyllosilicate, or other material, and adhered to these surfaces in thicknesses of one or more molecules. The term “water” (rather than “H₂O”) is not precisely used here because “water” is a (liquid) phase. Elevated temperatures, typically 110^oC for 12 hours, can desorb the adhered H₂O. However, for phyllosilicates, a temperature of 110^oC may not liberate all the adsorbed water molecules present, and temperatures of as high as 300^oC (in special cases, even higher) may be needed for some vermiculites and smectites.
Syn. absorbed water
Cf., water, structural