Fig. 3
From: Trachyte weathering in the urban built environment related to air quality
SEM-BSE photomicrographs showing different features of the carbonaceous fraction (darker in the images) detected on the weathering crusts and patinas of Euganean trachyte and its microchemical composition by EDS measured on two different spots (signal from gold coating is also visible). a Cluster of subspherical carbonaceous particles. b Microcracked patina with crumbled fine-grained feldspars. c Carbonaceous mass with Fe oxides, carbonates, and quartz. d Aggregates of carbonaceous particles arranged along the edges and the internal fractures of a plagioclase phenocryst