Abstract
Hydrous minerals such as serpentine can be heated by the microwave. A hydrous mineral can be distinguished from an anhydrous one by heating them together in the microwave. This can be applied, for example, to distinguish obsidian from pitchstone and peridotite from serpentinite. This is also good for education to show that some earth's rocks contain water in their minerals. Water and serpentinite with about 10 per cent H2O of the same 100 g mass are heated in the microwave for 40 sec., and then are put into cold water. The serpentinite cause more increase in temperature of the cold water than the heated water. This indicates that the energy absorbed in a hydrous material does not correlate with its H2O content.
