Ferrous Minerals Ratio

 "The ferrous minerals ratio highlights iron-bearing materials. It uses ratio between the SWIR band and the NIR band.

Ferrous Minerals Ratio = SWIR / NIR

    SWIR= pixel values from the short-wave infrared band
    NIR = pixel values from the near infrared band

Reference: Segal, D. "Theoretical Basis for Differentiation of Ferric-Iron Bearing Minerals, Using Landsat MSS Data." Proceedings of Symposium for Remote Sensing of Environment, 2nd Thematic Conference on Remote Sensing for Exploratory Geology, Fort Worth, TX (1982): pp. 949-951." (ESRI, 2018)

Sources

"Indices gallery". ArcGIS Pro, ESRI. 2018. 
http://pro.arcgis.com/en/pro-app/help/data/imagery/indices-gallery.htm.
Accessed February 1, 2019.