The amorphous content was the second largest component in
road dust at all the study sites. According to Fig. 2, the amorphous
content in soils ranged between 4.5% and 10%, which is in a similar
range as reported by Dawes et al. (2006). Amorphous content could
be due to partially weathered minerals (non-crystalline mineral),
certain clay minerals present in low content (that do not contribute
to diffractograms due to the limit of detection), amorphous silicate
(non-crystalline quartz) and organic matter, as noted by Bish
and Post (1989). However, the amorphous content in road dust was
10–40% higher compared to the soil samples. On average, the organic
matter content in the road dust samples were