Figure F4. Octahedral cation total vs. interlayer cations for smectites, talc, and serpentine. Formulas calculated as smectites (total layer charge = 44; all Fe as Fe2+). Smectites are saponite except where noted. See "Phyllosilicate Mineralogy," p. 4, in "Results" for discussion.

Figure F4. Octahedral cation total vs. interlayer cations for smectites, talc, and serpentine. Formulas calculated as smectites (total layer charge = 44; all Fe as Fe²⁺). Smectites are saponite except where noted. See "Phyllosilicate Mineralogy" in "Results" for discussion.