Fig. 17From: The impact of hydrothermal alteration on the physiochemical characteristics of reservoir rocks: the case of the Los Humeros geothermal field (Mexico)SEM images showing (a) amygdales filled with chlorite, epidote, and quartz, (b) alteration rims near larger feldspar phenocrysts, (c-d) epidote s. l. and quartz filling vugs (c) and veins (d), and pervasive silicification and relicts of phenocrysts in andesitic lavas. f metasomatic vein in fractured marble with wollastonite, garnet and apatite. Note the abundance of secondary porosity (black) in (c) to (f). Abbreviations: Adr = andradite, Ap = apatite, Cal = calcite, Ccp = chalcopyrite, Chl = chlorite, Ep = epidote, Fsp = feldspar, Grs = grossular, Kfs = K-feldspar, p = pores, Pl = plagioclase, Py = pyrite, Qz = quartz, Wol = wollastoniteBack to article page