SOME GENERAL CONSIDERATION'S 



9 



following list will give some idea of the minerals normally 

 present in soils : — 



COMMON SOIL-FOEMING MINERALS 



Quartz. . Si02 



Orthoclase K2O . AI2O3 . 6 Si02 



Plagioclase NagO . AI2O3 . 6 Si02, CaO . AI2O3 . 2 SiOs 



or combinations 

 Hornblende Chiefly Ca(MgFe) 3814012 with 



Na2Al2Si40i2 and (MgFe)2 . (AlFe)2 • 



Si20l2 



Chiefly CaMgSi206 

 (AlFe)2Si206 



2 H2O . K20 . 3 AI2O3 . 



1. 



3. 



5. Augite 



with (MgFe) 



6. 



Muscovite 



7. 



Biotite . . 



8. 



Olivine 



9. 



Serpentine 



10. 



Epidote 



11. 



Apatite 



12. 



Zircon . 



13. 



Chlorite 



14. 



Calcite 



15. 



Dolomite 



16. 



Gypsum 



17. 



Talc . 



18. 



Hematite 



19. 



Siderite 



20. 



Limonite 



21. 



Kaolinite 



22. 



Zeolites 



esiOs 





III 



or 



(HK)2 (MgFe)2 (AlFe)2 (Si^s 



2 (MgFe)O . Si02 



3 MgO . 2 Si02 . 2 H2O 

 H2O . 4 CaO . 3 (AlFe)203 . 6 SiOi 

 3 CasPzOg + (CaFy or (CaCl^) 



combinations 

 Zr02 . Si02 



H40 (FeMg) 23AI14S113O90 

 CaCO, 



CaCOs . MgCOa 

 CaSOi . 2 H2O 

 H20.3Mg0.4Si02 

 Fe203 

 FeCOs 



2 Fe203 . 3 H2O 

 2 H2O . AI2O3 . 2 SiOa 

 Complex hydrated aluminium silicates of 



Ca, K, and Na as Philolite (CaK2N2) 



AlaSiioOa* - 5 H2O 



