SEARCH Articles Figures Tables Alteration clay mineral Gangue and alteration minerals Magnesium-rich minerals, alteration Meguma Supergroup, Nova Scotia, Canada petrographic constraints, depositional environments and alteration haloes about sediment hosted hydrothermal mineral deposits Petrographic characterization of propylitic alteration associated with porphyry Cu-Mo deposits in the Collahuasi District. Northern Chile implications for mineral exploration