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In alchemy, chalcanthum, also called chalcanth or calcanthum, was a term used for the compound blue vitriol (CuSO4), and the ink made from it. The term was also applied to red vitriol (a native sulfate of cobalt), and to green vitriol (ferrous sulfate).
- This article incorporates text from a publication now in the public domain: Chambers, Ephraim, ed. (1728). "article name needed". Cyclopædia, or an Universal Dictionary of Arts and Sciences (first ed.). James and John Knapton, et al.
- Webster's Revised Unabridged Dictionary (1913)