1. Building Soil Minerals

2. EXPECTED ION CORRDINATION

3. BOND VALENCE

5. Clay Minerals

6. BUILDING BLOCKS

7. Si 6 O 18

8. Tetrahedral Sheet Side View (100) plane Top View (001) plane

9. Structural Views: Anion Sheets

10. Creating Octahedral Sheets - Filling of Anion Sheets Dioctahedral (trivalent ions) and Trioctahedral (divalent ions)

11. (di)OCTAHEDRAL SITE FILLING Anion Sheet with Trivalent (Al 3+ ) Cations

12. (di)OCTAHEDRAL SITE FILLING Dioctahedral Sheet Without Basal Hydroxyls

13. Octahedral Sheets Trioctahedral (divalent cation) Dioctahedral (trivalent cation) View down [001] axis x y

14. Charge Development Isomorphic substitution Terminal (unsatisfied) bonds

15. Charge Development Isomorphic Substitution Tetrahedral Sites: Al 3+ for Si 4+  (-) charge Octahedral Sites: Mg 2+ + for Al 3+  (-) charge Al 3+ for Mg 2+  (+) charge

16. surface Charge Development Terminal (unsatisfied) bonds - bond valence considerations

17. Minerals within Soils

18. Rock Entisol Inceptisol Alfisol Ultisol Oxisol Mollisol Vertisol (clay mineralogy) Ideal Weathering Series

19. Rock Entisol Inceptisol Alfisol Ultisol Mollisol Oxisol

20. Phyllosilicates: Clay Minerals Entisol Inceptisol Alfisol Ultisol Mollisol - Phyllosilicates dominate the clay size particles of most soils

21. General Classes (layer build-up) of Phyllosilicate Minerals

22. Octahedral Minerals Oct. Brucite, Mg(OH) 2 Gibbsite, Al(OH) 3

23. H-bonds 1:1 Phyllosilicates tet oct Sheets } 1:1 layer Kaolinite and Serpentine

24. Kaolinite: Al 2 Si 2 O 5 (OH) 4 - dioctahedral, 1:1 mineral

25. Sharing of Apical Oxygens in Tetrahdral Sheet with Hydroxyls of Two Octahedral Sheets tet oct tet Talc (2:1 trioctahedral mineral)

26. Phlogopite: KMg 3 (AlSi 3 O 10 )(OH) 2 Biotite: KFe 3 (AlSi 3 O 10 )(OH) 2 Muscovite: KAl 2 (AlSi 3 O 10 )(OH) 2 Micas tet oct tet oct tet K+K+ K+K+ K+K+ Unit layer of charge

28. K+K+K+K+

29. Si 6 O 18 Ditrigonal (hexagonal) Cavity

30. Illite (hydrous mica) Vermiculite Smectite Expandable 2:1 Layer Phyllosilicates tet oct tet oct tet K+K+ H2OH2O Ca 2+ H2OH2O H2OH2O Illite:  KAl 1.3 Fe 0.4 Mg 0.2 Si 3.4 Al 0.6 O 10 (OH) 2

31. Vermiculite dioctahedral:  Na x (Al,Fe) 2 (Si 4-x Al x )O 10 (OH) 2 n H 2 O trioctahedral:  Na x (Mg,Fe) 3 (Si 4-x Al x )O 10 (OH) 2 n H 2 O Expandable 2:1 Layer Phyllosilicates tet oct tet oct tet K+K+ H2OH2O Ca 2+ H2OH2O H2OH2O

32. Expandable 2:1 Layer Phyllosilicates Smectite Dioctahedral Forms: Montmorillonite  Na x (Al 2-x Mg x )Si 4 O 10 (OH) 2 Beidellite:  Na x (Al 2 )(Al x Si 4-x )O 10 (OH) 2 Trioctahedral Forms: Saponite:  Na x-y (Mg 3-y Al y ) 3 (Si 4-x Al x )O 10 (OH) 2 Hectorite:  Na x (Mg 3-x Li x ) 3 Si 4 O 10 (OH) 2

33. Interlayer Expansion Two Dominant Factors: 1. Structural Charge 2. Interlayer Ion

34. [Mg 2 Al 1 (OH ) 6 ]Mg 3 (Si 3 Al)O 10 (OH) 2 2:1:1 Layer Phyllosilicates

35. oct (b) 2:1:1 Layer Phyllosilicates Hydroxy Interlayer Vermiculite (HIV) Hydroxy Interlayer Smectite (HIS) - pedogenic chlorites versus true chlorites tet oct tet oct tet [Mg 2 Al 1 (OH ) 6 ]Mg 3 (Si 3 Al)O 10 (OH) 2

36. Iron Oxides Aluminum Oxides Manganese Oxides Accessory Minerals

37. Andisol - volcanic ash Hydrous Silicates and Aluminosilicates Accessory Minerals

38. Hydrous Silicates and Aluminosilicates Accessory Minerals 100 nm

39. Identifying Soil Minerals X-ray Diffraction

40. Useful (Common) Methods/Approaches Optical Microscopy Infrared Spectroscopy Thermal Analysis X-ray Diffraction (XRD) Physical Properties

41. X-ray Diffraction Attributes Limitations

42. X-ray Diffraction: Foundation Consider wave properties

43. X-ray Diffraction: Foundation Constructive versus Destructive Interference

44. X-ray Diffraction: Foundation Bragg’s Law: n = 2d sin   d  wavelength   to 2.5 Å)

45. General Classes (layer build-up) of Phyllosilicate Minerals

46. Trioctahedral Phyllosilicate Minerals Sheets Octahedral Layer Only: Brucite, Mg(OH) 2 Oct. 1:1 Mineral: Serpentine, Mg 3 Si 2 O 5 (OH) 4 Tet. Oct. Tet. Oct. Tet. 2:1 Mineral: Talc, Mg 3 Si 4 O 10 (OH) 2 Layer Build-up: z y

47. MineralMg 2+ K+K+ Glycerol550 C Kaolinite777- Mica10 Vermiculite14101410 Smectite14-1612-141810 HIV14 10-11 HIS14-16141810-11 XRD: Chemical Treatment d-spacing, Angstroms

48. Octahedral Minerals Oct. Brucite, Mg(OH) 2 Gibbsite, Al(OH) 3

49. Serpentine: Mg 3 Si 2 O 5 (OH) 4 - trioctahedral Kaolinite: Al 2 Si 2 O 5 (OH) 4 - dioctahedral

50. Phlogopite: KMg 3 (AlSi 3 O 10 )(OH) 2 Biotite: KFe 3 (AlSi 3 O 10 )(OH) 2 Muscovite: KAl 2 (AlSi 3 O 10 )(OH) 2 Micas tet oct tet oct tet K+K+ K+K+ K+K+

51. Illite Vermiculite Smectite Expandable 2:1 Layer Phyllosilicates tet oct tet oct tet K+K+ H2OH2O Ca 2+ H2OH2O H2OH2O

52. oct (b) 2:1:1 Layer Phyllosilicates Hydroxy Interlayer Vermiculite (HIV) Hydroxy Interlayer Smectite (HIS) - pedogenic chlorites versus true chlorites tet oct tet oct tet [Mg 2 Al 1 (OH ) 6 ]Mg 3 (Si 3 Al)O 10 (OH) 2