blue vitriol; chalcanthite
Technical term for copper(II) sulfate pentahydrate, a blue crystalline mineral. Used in chemistry, mineralogy, and traditional contexts.
Blue vitriol is used in copper refining and as a pigment.
This crystal is a type of copper sulfate called chalcanthite.
Standard kanji spelling for this mineral term.
Irregular kanji usage variant; 丹 is not the standard character for this word.
From Chinese 膽礬／胆矾 (dǎnfán), literally 'gall alum', referring to its bitter taste and crystalline appearance. The Japanese reading たんばん is the on'yomi of the kanji.