The mineral name “maufite” was proposed in 1930 to describe a “bright emerald green” nickeliferous vein material occurring within a serpentinite of the Great Dyke in the Umvukwe Range of Zimbabwe, then Southern Rhodesia. Study of this material shows that it is not a distinct species but rather an interstratified nickel-bearing lizardite-clinochlore, with lizardite dominant over clinochlore. The name “maufite” is discredited. The lizardite is a Group-A polytype, and the clinochlore is a Ia polytype in the nomenclature developed by S.W. Bailey. The formula calculated on the basis of 14 negative charges is (Mg1.74Al0.88Ni0.13□0.25)Σ3.00(Si1.60Al0.40)Σ2.00O5(OH)4; on the basis of nine oxygen atoms including 14.6 wt.% H2O determined thermogravimetrically, the formula is (Mg1.68Al0.78 Ni0.13□0.41)Σ3.00(Si1.55Al0.45)Σ2.00O4.51(OH)4.49. Analytical electron microscopy shows that the composition is variable on a fine scale. The randomly interstratified lizardite-clinochlore occurs as a pseudomorph after amphibole and plagioclase and is a product of serpentinization. The material is poorly crystalline and very fine grained, producing broad reflections on powder diffraction and microbeam X-ray diffraction patterns. Unlike most of the interstratified serpentine-chlorite described in the literature, lizardite is here dominant over clinochlore.
- interstratified lizardite-clinochlore
- nickel-bearing lizardite
- powder XRD
- microbeam XRD
- evolved gas analysis
- electron-microprobe analysis
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