chrome alum

English Thesaurus

1. a violet-colored salt used in hide tanning and as a mordant in dyeing (noun.substance)

hypernym	:	mordant,
definition	:	a substance used to treat leather or other materials before dyeing; aids in dyeing process (noun.substance)

hypernym	:	salt,
definition	:	a compound formed by replacing hydrogen in an acid by a metal (or a radical that acts like a metal) (noun.substance)