Lexicon

Head of Serapis

Gypsum 
Gysum origin: Egypt

Gypsum has been used in Egypt for thousands of years. Deposits are known near Alexandria and Port Saïd, along the Suez Golf cost, in the Fayoum area, at Qoseir and north of Ourghada on the Red Sea. Thus a local source close by its discovery is most probable.

D. Decrouez & K. Ramseyer (1998)