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6879986 
Journal Article 
The composition of chrysotile and its relationship with lizardite 
O'Hanley, DS; Dyar, MD; , 
1998 
Yes 
Canadian Mineralogist
ISSN: 0008-4476
EISSN: 1499-1276 
MINERALOGICAL ASSOC CANADA 
NEPEAN 
36 
727-739 
WOS:000076767200004 
Mossbauer data were obtained from 14 specimens of chrysotile taken from three geologically well-characterized serpentinites. These data were used in conjunction with results of electron-microprobe (major elements) and uranium-extraction analyses (H2O) to generate a comprehensive set of compositions for chrysotile. Chrysotile contains both Al and Fe3+ as secondary tetrahedrally coordinated cations, with Al dominating over Fe3+. The proportion of Fe-[4](3+) and Fe-[6](3+) shows an inverse correlation that preserves a relatively constant total Fe3+ content. Most specimens have low Fe3+/Fe2+. The incorporation of trivalent cations is greater in the sheet of octahedra than in the sheet of tetrahedra, suggesting the presence of H+ vacancies; this result is consistent with measured H2O contents. The Mossbauer parameters for chrysotile are similar but more scattered than those for lizardite, suggesting minimal differences in coordination polyhedra between the two minerals. However, chrysotile and lizardite are not polymorphs in natural systems. Compared to the associated lizardite, chrysotile contains more Fe2+ and Al-[4] and fewer Fe-[4](3+) ions and Hi vacancies. These data support the hypothesis that high Fe2+ content and H+ vacancies contribute to the replacement of lizardite by chrysotile, and vice versa, during serpentine replacement. 
chrysotile; Mossbauer spectroscopy; electron-microprobe data; uranium-extraction analysis; lizardite; phase relations; serpentine replacement; serpentinization