1979 Niger - Bororo women dancers. Annual feast of the Bororos
Here are images of the two airmail stamps in a set depicting M'Bigou stone sculptures of a woman's head and of a man's head, designed and engraved by Jean Pheulpin, and issued by Gabon on July 5, 1973, Scott Nos. C141 & C142.
Stamp from Ghana via 'Stamps from the African Diaspora'
Google Image Result for http://www.chinadaily.com.cn/photo/images/attachement/jpg/site1/20130105/001aa018f8021251d92737.jpg