The surface structure of the layer silicate mineral chlorite has been imaged at near-atomic resolution using an atomic force microscope (AFM). The chlorite structure consists of a 2:1 talc-like layer and a brucite-like interlayer sheet. The AFM clearly resolves the OH groups of the brucite-like interlayer sheet and the bases of the SiO4 tetrahedra of the talc-like sheet. The imaged surface structures of both the talc- and brucite-like layers are generally consistent with that of the bulk structure. The mean unit-cell distances (a = 5.31 ± 0.31, b = 9.74 ± 0.80 Å) are within 1 and 5%, respectively, of those calculated for the known structure. However, some structural relaxation of the talc-like surface is observed. This relaxation manifests itself as a systematic shortening and elongation of both a and b across the layer and probably results from a concertina-like readjustment of the surface after cleaving. The brucite-like layer does not exhibit similar behavior.

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