On the basis of the outlines of the crystallochemical classification of chlorites (Wiewióra & Weiss 1990), the authors postulate regression equations for the b parameter, derived from the published structural and chemical data of chlorites:
— trioctahedral chlorites
b=9.225+0.0270Al^IV-0.0386Al^VI+0.0376Fe²⁺ -0.0376Cr³⁺ +0.0665Mn²⁺
— di-tri- and di-dioctahedral chlorites
b=8.860+0.112Al^IV+0.0524Mg²⁺+0.0752Fe²⁺+O.0600Fe³⁺ -0.0523Li⁺
These equations, together with the similar regression equation for d₍₀₀₁₎ derived by Raussel-Colom, Wiewióra & Matesanz (1991), were used to prepare 2D and 3D diagrams. They may be used for estimation of the chemical composition of any chlorite from the XRD analysis.