Fig. 6: Phyllosilicate clay van der Waals minerals.

a, d Three-dimensional representation of the crystal structure of talc168 and vermiculite169. b, e Pictures of mineral rocks of talc and vermiculite13, respectively. c Optical microscopy image of a talc flake, mechanically exfoliated from the bulk crystal shown in b. f Picture of thermally expanded vermiculite13. e, f Reproduced from ref. 13, with permission.