Clay Minerals Building block: Al Octahedra Al(OH) 6
Slide 5
Clay Minerals SiSi O Al OH Octahedral Layer Tetrahedral Layer
Dominantly formed by hydrolysis and hydration
Slide 6
Clay Minerals
Slide 7
http://faculty.yc.edu/ycfaculty/ags105/week08/soil_colloids/soil_colloids_print.html
Scanning Electron Microscope (SEM) image of Kaolinite
Slide 8
http://greenfieldgeography.wikispaces.com/IGCSE+and+GCSE+Weathering
Hydrolysis: H + replaces a cation in a mineral 4KAlSi 3 O 8 + 4H +
+ 2H 2 O 4K + + Al 4 Si 4 O 10 (OH) 8 + 8SiO 2 Weathering granite
forms grus Potassium feldspar Kaolinite (clay) Formation of Clay
Minerals via Weathering
Slide 9
Clay Minerals and Progressive Weathering O T T O T T Cations O
T T O T T Weathering O T O T O O
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Clay Minerals Why are clay minerals so important on Earths
surface?
Slide 11
Clays exhibit shrink-swell behavior because of their ability to
hold water Clay Function #1: They Hold Water!
Slide 12
Cation Exchange: Exchange of cations between minerals and
solutions http://www4.uwsp.edu/geo/faculty/lemke/geomorphology/
Commonly exchanged cations: H +, K +, Na + Ca 2+, Mg 2+ Al 3+ Clay
or organic compound Clay or organic compound
http://elements.geoscienceworld.org/content/6/6/375/F2.expansion.html
Clay mineral Exchangeable cations Clay Function #2: They Hold
Nutrients!
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Beware: Clay versus Clay or to a specific grain size (
