L1 /
9
CH3041
CLAYS III
• Formation of montmorillonite from orthoclase
feldspar occurs by weathering.
eg. 2KAlSi3O8 +
0.25Mg2+ + H+ + 5H2O ® 2.25Si(OH)4
K+0.5(Al1.75Mg0.25) (Si3.75Al0.25)O10(OH)2 + 1.5K+
K+0.5(Al1.75Mg0.25) (Si3.75Al0.25)O10(OH)2 + 1.5K+
There are a variety of other solid inorganic
materials in soils.
materials in soils.
• Allophane:
structurally disordered aluminosilicates found in volcanic clays.
• Oxides, hydroxides and
oxyhydroxides:
esp. a-FeOOH (goethite), Al(OH)3 (gibbsite).
esp. a-FeOOH (goethite), Al(OH)3 (gibbsite).
The final
result of weathing of clay minerals smectite
& kaolinite & also from 1o silicates.
