Hi

Please see this link:

Article Mapping evaporate minerals by ASTER

you have to follow these steps:

1-Map metamorphic rocks in the areas

2-Map foliation zones or parallel fractured zones that may be exposed to high tectonic compression force

3-For better discrimination,

(I)apply RGB decorrelation stretch to the image ,

(ii) Apply suitable band ratio, Forward and invers P. Components analysis

and Forward and invers MNF rotation using Transform tool implemented in ENVI software

(iii) apply density slicing to the final image to highlight zones of mica (white or black depending on the chemical composition

Best wishes