Cesium Alum Crystals
Transmitted Crossed Polarized Light with Red Plate Compensator

Aluminum in dilute sulfuric acid solution can be detected with cesium sulfate. These
characteristic isotropic crystals,combinations of cubic and octahedal habits, indicate
the presence of aluminum. This is a standard micro-chemical test from the HANDBOOK OF
CHEMICAL MICROSCOPY, by Chamot and Mason. The bright blue and yellow crystals in this
field of view are gypsum crystals, the result of the presence of calcium in this solution.