Geoscience Reference
In-Depth Information
Fig. 1.2
Electron scanning microscope picture of various quartz grains (Dress et al.
1989
)
soil, quartz generally is found in sand and silt fractions, the amount of silica
mineral being determined by the parent material and the degree of weathering.
1.1.2 Clay Minerals
Clay minerals are natural nanomaterials that constitute the smallest particles in the
subsurface. They are defined as the fraction of particles smaller than a nominal
diameter of 2 lm. Many clay minerals have layer structures in which the atoms
within a layer are strongly bound to each other, with the binding between layers
being weaker. As a consequence, each layer can behave as an independent
structural unit. Several layer arrangements exist, but they do not differ greatly in
