The loss on ignition is reported as part of an elemental or oxide analysis of a mineral. The volatile materials lost usually consist of combined water (hydrates and labile hydroxy-compounds) and  carbon dioxide from carbonates. It may be used as a quality test, commonly carried out for minerals such as  iron ore.  For example, the loss on ignition of fly ash  is composed of contaminants and unburnt fuel.
In pyroprocessing industries such as lime,calcined bauxite, refractories or cement manufacture, the loss on ignition of the raw material is roughly equivalent to the mass loss it will experience in a  kiln. Likewise, in minerals, the loss on ignition indicates the material actually lost during smelting or refining in a furnace or smelter. The loss on ignition of the product indicates the extent to which the pyroprocessing was incomplete. ASTM tests are defined for limestone and lime and cement among others.