DDL and isomorphic substitution
Fragment of a discussion from Course talk:APBI200/Archive/2016-17WT2
Isomorphic substitutions lead to formation of negative charges on phyllosilicates. These negative charges then attract electrostatically cations and those attracted cations form DDL.
Particles without any charges (e.g. sand) do not have any attracted ions on their surfaces or, in other words, sand particles do not have DDL