Eosin
Sorry, this is incorrect. Eosin is a bright-red synthetic dye that is made from coal tar. There are various versions of the dye with different substituents on the anthracene and thus changing the hue and intensity of the color. Eosin is used in medicine and microbiology to stain cells and microorganisms. Most importantly it is used in blood and bone marrow studies. Eosin is also used for dying fabric such as wool, silk, and nylon.