Purple fluorite: A little known artists' pigment and its use in Late Gothic and Early Renaissance painting in Northern Europe

A purple calcium fluoride, CaF2, a natural inorganic pigment, has been iden tified on a small number of painted artworks from c1450 to 1520. It was use d on panel painting, polychrome wooden sculptures, wall paintings and archi tectural polychromy from Souther Germany, Tyrol (Austria), Switzerland, Sil esia (Poland) and Hungary. Fluorite was identified as an artists' pigment i n 1968, but this case was first published in 1986. An intensely blackish-pu rple type of fluorite called antozonite (German: Stinkspat) was probably us ed for this pigment. Paint layer reconstructions of some of the paintings w here fluorite was identified clearly illustrated its function and character istics together with various pigments and binding media. Due to its poor ti nting and hiding power, it was often used to enhance a colour effect in a p igment mixture. It was also used in combination with lead white to obtain a purple colour. Fluorite can only be identified with certain analytical met hods, the most important being microchemical analysis, polarized light micr oscopy (PKM), and X-ray diffractometry (XRD). Further analysis with total r eflection X-ray fluorescence analysis (TRXFA) can be applied to identify tr ace elements and possibly the sources of this pigment.