Hello Raju,
Yes, alkali sulphate can be identified and quantitatively estimated by clinker microscopy. Alkali sulphates appear as black, irregular structures... most often occurring within pores.
Since crystal counting is a statistical method, the accuracy is related to the total area of the sample that is scanned and counted. However reasonable accuracy can be obtained by an experienced microscopist using modern microscopy techniques.
Estimation of alkali sulphates by microscopy invariably gives results that are lower than that calculated from XRF chemical analysis, because not all of the alkali and sulphur is present as alkali sulphates. Both may be present in solid solution within the crystal
structure of the clinker minerals and so cannot be seen under the microscope.
Regard,
Ted.