Chemical differences among the serpentine “polymorphs”: a discussion

Many of the serpentine mineral analyses treated statistically by Page (1968) do not conform to the standards he proposed for characterisation of the specimen or for completeness of analysis. When these unsatisfactory analyses are omitted the remainder are inconsistent with Page's conclusions that lizardite has relatively high SiO₂ and low Al₂O₃ contents and that antigorite has relatively large numbers of trivalent tetrahedral ions. They are consistent with his other conclusions that relative to one another chrysotile is low in Al₂O₃, lizardite is low in Fe²⁺ and Fe²⁺: Fe³⁺, and antigorite is high in SiO₂ and low in MgO and H₂O+. It is further shown that chrysotila and lizardite contain H₂O+ in excess of the ideal formula, antigorite has the highest FeO/(FeO+Fe₂O₃+Al₂O₃) aid lizardite the lowest. The extents of substitution by Fe and Al tend to be in the order chrysoltile< lizardite< 6-layer serpentine, though the ranges overlap, and substitution in antigorite extends over the range of all the other species.