Alizarin (also known as 1,2-dihydroxyanthraquinone, Mordant Red 11, C.I. 58000 and Turkey Red) is an organic compound with the formula C14H8O4 that has been used throughout history as an important red dye, mainly for dyeing fabrics. . Historically it was extracted from the roots of plants of the genus Madder. In 1869, it was the first synthetically produced natural dye. Alizarin is the key ingredient in making the craziest lake pigments known to painters as craziest pink and alizarin violet. Alizarin is dark red in the most common use of the term, but the term is also part of the name of several related non-red dyes, such as Alizarin Cyanine Green and Alizarin Brilliant Blue. One notable use of alizarin in modern times is as a dye in biological research, staining free calcium and some calcium compounds red or light purple. Alizarin continues to be used commercially as a red fabric dye, but to a lesser extent than in the past.