Chlorites from volcanic-sedimentary sequences, hosting the Borromeo Co-pyrite ores in the Upper Martello Valley (Italy), occur in phyllites of upper greenschist facies. Chlorites in the ore-mineralized phyllites are chamosites with a Fe/(Fe + Mg) ratio of 0.59-0.71; 2 samples from host phyllites are clinochlore with a Fe/(Fe+Mg) ratio of ∼0.40. The IIb polytype prevails in most chlorites. The presence of the metastable Ib polytype correlate with higher Fe-content. Possible diagenetic relicts exhibited by the chlorite-Ib polytypes suggest a premetamorphic origin.
Chlorites from cobalt pyrite horizons, Upper Martello Valley (Alto Adige, Northern Italy) / Brigatti, Maria Franca; Casari, L.. - In: NEUES JAHRBUCH FUR MINERALOGIE MONATSHEFTE. - ISSN 0028-3649. - STAMPA. - 1988:(1988), pp. 547-558.
Chlorites from cobalt pyrite horizons, Upper Martello Valley (Alto Adige, Northern Italy)
BRIGATTI, Maria Franca;
1988
Abstract
Chlorites from volcanic-sedimentary sequences, hosting the Borromeo Co-pyrite ores in the Upper Martello Valley (Italy), occur in phyllites of upper greenschist facies. Chlorites in the ore-mineralized phyllites are chamosites with a Fe/(Fe + Mg) ratio of 0.59-0.71; 2 samples from host phyllites are clinochlore with a Fe/(Fe+Mg) ratio of ∼0.40. The IIb polytype prevails in most chlorites. The presence of the metastable Ib polytype correlate with higher Fe-content. Possible diagenetic relicts exhibited by the chlorite-Ib polytypes suggest a premetamorphic origin.
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