The Hydrogrossular Calibration

 

The integrated absorbance (total area under the curve in the OH region) can be related to the H2O content of the garnet.
 
 

Infrared spectrum of synthetic katoite The grossular calibration
 

We can ask the following question:  'Does this calibration line applies to low concentrations of OH in the nominally anhydrous minerals?'
 

Reference:  Rossman GR, Aines RD (1991) The hydrous components in garnets: grossular - hydrogrossular. American Mineralogist 76, 1153-1164.