A small stone vial discovered in southeastern Iran contained a red cosmetic that was likely used as a lip coloring nearly 4,000 years ago, according to archaeologists, reports CNN.

The rare find is “probably the earliest” example of lipstick to be scientifically documented and analyzed, the researchers reported in February in the journal Scientific Reports.

More than 80% of the analyzed sample was made up of minerals that produce a deep red color—primarily hematite. The mixture also contained manganite and braunite, which have dark hues, as well as traces of other minerals and waxy substances made from vegetables and other organic substances.

It is not possible to exclude the possibility the cosmetic was used in other ways, say, as a blusher, according to lead study author Massimo Vidale, an archaeologist at the University of Padua’s Department of Cultural Heritage in Italy. But he said the homogenous, deep red color, the compounds used and the shape of the vial “suggested to us it was used on lips.”