Soil Minerals  
Most secondary, arise from weathering

    Composition     -    kinds and relative quantities of ions
                                     -   ratios inherent in chemical formula

    Structure            -   spatial arrangement of ions
                                     -   gives color, hardness, crystal shape, cleavage

    Orderedness

        Crystalline      -  orderly and repeated spatial pattern
                                          slow crystallization, more stable, less soluble

          Amorphous      -   No organized structure, but constant composition
                                               Rapid crystallization, less stable, more soluble