For zeolites, the charge distribution within the structure is important, and in order to establish a measure of this distribution, we consider the cationic valences surrounding each oxygen atom. These are expressed by the sum of the cationic bond strengths around the O atoms with the specified coordinations, discussed in a preceding paper. New parameters expressing the relative excess or deficiency in the sum of the cationic bond strengths to oxygen compared to 2 valence units are defined. They

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... are related to the so-called "identifiers for the coordination of O atoms", which were defined in a preceding paper, by an analysis which follows the ßowr's exfenctetf e/ecrros/ar/c va/ence rw/e. A relation between cationic valences and the O coordinations is thus established for the O atoms coordinated to Al atoms or cavity cations. Following a scheme for possible charge transfer within zeolite structures, limiting conditions for a ".Vr«c/«ra/" compost/ton of these minerals are deduced. Thus, for structures of Si and Al-bearing zeolites, there are, at least, on average, two O atoms, whose sum of the bond strengths is below 2 valence units, which, linked to the Al atoms, from part of these O tetrahedra; there are further, per Al atom, between 1 and 4 water molecules which belong to the cavity cations polyhedra; finally, a limit between zeolites with a/ow watercon/enr and zeolites with a /ttg/t water content is drawn in terms of the O coordinations.