Raman spectroscopic analysis of a tembetá: a resin archaeological artefact in need of conservation.

The Raman spectroscopic analysis of a Brazilian tembetá, a lip-plug which signifies the attainment of manhood in tribal cultures, and dated to about 1600 years BP is reported. Tembetá are usually made of wood or stone but this lip-plug is very rare in that it is made of resin, which has been severely degraded in the burial environment; the brownish-red fragmented remains are in an extremely fragile condition and information about the chemical composition was required before urgent conservation was undertaken. Raman spectra excited at 1064 nm showed the presence of triterpenoid materials in the main body of the artefact, and indicated that the red-brown coating was not iron(III) oxide as suspected but rather degraded resin.