Editing Alum (section)

===Alum described in medieval texts===
Alum and [[Iron(II) sulfate|green vitriol]] (iron sulfate) both have sweetish and astringent taste, and they had overlapping uses. Therefore, through the [[Middle Ages]], alchemists and other writers do not seem to have distinguished the two salts accurately. In the writings of the [[Alchemy|alchemists]] we find the words ''misy'', ''sory'', and ''chalcanthum'' applied to either compound; and the name ''atramentum sutorium'', which one might expect to belong exclusively to green vitriol, applied indiscriminately to both.{{citation needed|date=June 2023}}

Alum was the most common [[mordant]] (substance used to set dyes on fabrics) used by the dye industry, especially in Islamic countries, during the [[Islamic Golden Age|middle ages]]. It was the main export of the [[Chad]] region, from where it was transported to the markets of [[Egypt]] and [[Morocco]], and then to [[Europe]].  Less significant sources were found in Egypt and [[Yemen]].<ref name=Goitein-Sanders-1967/>