Chloritization(redirected from chloritisation)
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a metasomatic process in which the dark minerals of rocks and sometimes also the matrix itself are replaced by chlorites. Different types of chloritization are distinguished: regional postmagmatic chloritization of basic effusive rocks and their tuffs (seeGREENSTONE); chloritization of basic lavas associated with albitization (seeSPILITE) and of the dark minerals of acidic and intermediate igneous rocks (for example, the biotite and hornblende in granitoids); and hydrothermal chloritization of various rocks as a commonly occurring type of alteration near ores (seePROPYLITIZATION). The development of linear zones of chloritization indicates the presence of hydrothermal ore deposits.