almond is a double aluminium sulphate with astringent qualities known since ancient times. Some alunite deposits in the Maghreb and Sahara have been exploited sufficiently widely to refer to them by ancient and medieval sources. The richest of these deposits were arguably those of Kharga and Dakhhla in Egypt; El-Bekri cites the mines of Forferūn. The exploitation of these fields was probably abandoned as a result of the conc...