Fig. 10From: Trachyte weathering in the urban built environment related to air qualityThin-section photomicrographs of samples of Euganean trachyte with Fe-rich crusts, showing dispersion of fine-grained Fe oxides/hydroxides or Fe in amorphous state around a biotite crystal (left) and two opaque minerals (i.e., magnetite or ilmenite) (right), apparently indicating near-surface mineral leachingBack to article page