Fuchsine or rosaniline hydrochloride is a magenta dye with chemical formula C₂₀H₁₉N₃·HCl. There are other similar chemical formulations of products sold as fuchsine, and several dozen other synonyms of this molecule. It becomes magenta when dissolved in water; as a solid, it forms dark green crystals.

Formula: C20H20N3·HCl