Prima segnalazione di mineralizzazione a carbonati e silicati di magnesio

Cimino, G. and Oteri, F. and Saccà, Carmelo and Triscari, M. (1983) Prima segnalazione di mineralizzazione a carbonati e silicati di magnesio. Accademia Peloritana dei Pericolanti, Classe di Scienze FF. MM. NN., LXI. pp. 229-265.

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Abstract

Results achieved in a chemical and mineralogical research on a Mg-Ca-Fe-Mn carbonates mineralization, first observed close to Fiumedinisi on Peloritani Mts. (Sicily), are given. Ore-body occurs as an irregular fragment entrapped in the phyllites of the so-called «Mandanici Unit ». It consists primarily of abundant clusters and bunches of large, flat lens-shaped whitish crystals, resulting by an intimate intergrowth of magnesite and dolomite with minor calcite, talc and detrital, strained quartz grains, regrown in elongated arrangements that show some etching by the carbonate matrix. Outlines of crystals are marked by a thin film of blackish carbonaceous, extremely fine, powder, only in small part graphitic in composition. Despite the presence of quartz and calcite, wollastonite is totally absent, so indicating temperatures of about 400 C°. Interstices between laths of major carbonates are filled by a very fine-grained blackish aggregate of dolomite with minor leuchtenbergite, quartz and traces of magnesite. The carbonaceous stuff is ubiquitous and often it is a serious obstacle to microscopic observations.
Very rare tiny areas, light pink in colour, observed only in the whiter parts of the mineralization, proved to be an intimate intergrowth of abundant leuchtenbergite and minor sheridanite, dolomite and quartz. Carbonaceous stuff is practically absent. Relatively abundant among the trace elements are, Bi (69 ppm in the toutvenant and 97 ppm in the whitish crystals), Sn (30 and 158 ppm respectively) and V (21 and 24 ppm respectively), these last two never detected before in the whole Peloritani area. Due to the lack of significant deformations, a late Tertiary, Alpine age may be assigned to the mineralization. Its origin is explained on the assumption that paleozoic crystalline limestone, more or less marly and impure, interbedded within the phyllites of the Mandanici unt, where hydrothermally metamorphosed, in presence of adequate CO2 pressure and temperature not much higher than 350°C. The presence of several phyllosilicates namely tale, leuchtenbergite and sheridanite is bound to a supply of Mg, that together with Fe and Mn, may derive from scattered amphibolitic metamorphites, diffusely occurring on the Peloritani Mts. Considering a preceeding dose detection of a numher of W-bearing veins in the Fiumedinisi area, the new find of a quite complex Mg-bearing deposit — both never described before — constitutes a strong argument in favor of the opinion that the present-day status of knowledge about the intricate question of the Peloritani mineralizations, is by no means conclusive.

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