Vitriol
Vitriol is the general chemical name encompassing a class of chemical compounds comprising sulfates of certain metals – originally, iron or copper. Those mineral substances were distinguished by their color, such as green vitriol for hydrated iron(II) sulfate and blue vitriol for hydrated copper(II) sulfate.
These materials were found originally as crystals of sulfate minerals, formed by evaporation of groundwater that percolated through sulfide minerals and collected in pools on the floors of old mines. The word vitriol comes from the Latin word vitriolum, lit. 'small glass', as those crystals resembled small pieces of colored glass.
The historic alchemical symbol for vitriol is encoded in Unicode as U+1F716 🜖 ALCHEMICAL SYMBOL FOR VITRIOL.
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