Identification of 2: 1 clay minerals from compositional data

The methodology for classifying a clay mineral into its broad-group and sub-group levels from its compositional data, is presented here. The inputs include, total layer charge (TLC), K content, octahedral Al (VIAl), octahedral Mg (VIMg), tetrahedral charge (TC) and octahedral charge (OC). These are used as inputs in a simple computational procedure to obtain ‘classification scores’ that identifies the broad group and sub-group of a mineral. First a mineral is identified as a clay mica, smectite or vermiculite from its derived classification score. Subsequently, the clay mica is identified as an illite, glauconite or celadonite; a smectite is identified as a montmorillonite, beidellite, nontronite or saponite. Predicted classifications are significant at p < 1%. The method provides a reliable and rapid technique for identifying a 2: 1 clay mineral.