Fig. 7: Phyllosilicate mica van der Waals minerals.

a, d, g, j Three-dimensional representation of the crystal structure of muscovite170, biotite171, lepidolite172, and phlogopite173, respectively. b, e, h, k Pictures of mineral rocks of muscovite, biotite, lepidolite, and phlogopite, respectively. d, f, i, l Optical microscopy images of few layers flakes mechanically exfoliated from the bulk crystals shown in b, e, h, k, respectively.