A transparent crystal form of the mineral gypsum. This can occur in clays and is the cause of efflorescence.
Gypsum is hydrated calcium sulphate, CaSO4 2H2O. It is the crystalline mineral from which plaster is
Selenite at Wikipedia
A common problem with dry and fired ceramic. It is evident by the presence of a light or dark colored scum on the dry or fired surface.
|Sulfur evolution (425-650)
|By Tony Hansen
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