Photomicrographs of hydrothermal alteration in PPL. Cal: calcite; Chc: chalcedony; Hul: heulandite; Jar: jarosite; Mgs: magnesite; Trd: tridymite. A: Andesitic lava flow from north of Grande-Anse beach (BT19); B: Vein in andesitic lava flow from north of Grande-Anse beach (BT19); C: Debris flow from Amandiers beach (BT1); D: Vein in debris flow from south of Grande-Anse beach, at the bottom of Gros-Morne near Deshaies (BT21).