A study of the serpentine group minerals from serpentinite rocks (Northern Apennines) and from brucitic marble (Ala, Trento) is reported. The samples were examined by X-ray diffraction, thermal analysis (DTA, TG and derivative curves), electron microscopy, infrared absorption spectroscopy and chemical tests. The results show that the thermal and regional metamorphic environments form the same serpentine polymorph (the lizardite) with morphologic analogy and marked chrystallo-chemical differences. The serpentinite rocks contain lizardite (antigorite is absent) with different features in the bastitic and non bastitic fractions. Our studies may state that, when the serpentinite rock was subjected to hydrothermal or weathering transformation, during the post-tectonic period, tabular lizardite transformed progressively into listiform lizardite and then into fine-grained and coarse-grained clynochrysotile.
Referenze Bibliografiche
ALIETTI A. (1959) - Diffusione e significato dei minerali a strati misti delle serpentine mineralizzate a talco dell'Appennino Parmense, «Periodico di Min.», 28 (1), 65—110.
BRINDLEY G. W. e ZUSSMAN J. (1959) - Infrared absorption data for serpentine minerals, «Am. Miner.», 44, 185-188.
FARMER V. C. (1974) - The infrared spectra of minerals, «Mineralogical Society Monograph», 4, Ed. by V. C. Farmer. London.
FAUST G. T. e FAHEY J. J. (1962) - The serpentine group minerals, «U.S. Geol. Surv. Prof. Paper», 384A, 1-92.
LUCE R. W. (1972) - Identification of serpentine varieties by infrared absorption, «U.S. Geol. Surv. Prof. Paper», 750B, 199-201.
MORANDI N. (1969) - Marmo a brucite nella zona di Ala (Trento), «Atti Symp. Int. Giac. Min. Alpi», 11, 557-563.
MUMPTON F. A. (1974) - Characterization of chrysotile asbestos and other members of the serpentine group of minerals, «Siemens Review XLI, 7th Spec. Iss. - X-ray and Electron Microscopy News», 75—84.
MUMPTON F. A. e THOMPSON C. S. (1975) - Mineralogy and origin of the Coalinga Asbestos Deposit, «Clays and Clay Minerals», 23, 131-143.
PAMPUCH R. e PTAK W. (1970) - Vibrational spectra and the structure of laminar silicates of I : I type. II. Octahedral layer, «Polska. Akad. Nauk, Oddzial Krakowie, Prace Komisji Ceram., Ceram.», 14, 7-36.
RUSSEL J. D. (1974) - The infrared spectra of minerals, Ch. 2. «Mineralogical Society Monograph», 4, Ed. by Farmer V. C. London.
WHITTAKER E. J. W. e ZUSSMAN J. (1956) - The characterization of serpentine minerals, «Miner. Mag.», 31, 107-126.
WICKS F. J. e WHITTAKER E. J. W. (1975) - A reappraisal of the structures of the serpentine minerals, «Canadian Mineralogist», 13, 227-243.
YARIV S. e HELLER-KALLAI L. (1975) - The relationship between the I.R. spectra of serpentines and their structures, «Clays and Clay Minerals», 23, 145-152.
ZUSSMAN J., BRINDLEY G. W. e COMER J. J. (1957) - Electron diffraction studies of serpentine minerals, «Am. Miner.», 42, 133-153.
Con il contributo del Ministero per i Beni e le Attività Culturali