Alizarin Red S is used in histology and histopathology to stain, or locate calcium deposits in tissues.[1][3][4] In the presence of calcium, Alizarin Red S, binds to the calcium to form a Lake pigment that is orange to red in color.[4] Whole specimens can be stained with Alizarin Red S to show the distribution of bone, especially in developing embryos.[4] In living corals alizarin Red S has been used to mark daily growth layers.[5]
In geology, Alizarin Red S is used on thin sections, and polished surfaces to help identify carbonate minerals which stain at different rates.[6]
^Dickson, J. A. D. (1966). "Carbonate identification and genesis as revealed by staining". Journal of Sedimentary Research. 36 (4): 491–505. doi:10.1306/74D714F6-2B21-11D7-8648000102C1865D.