Raman investigation of ceramics from 16th and 17th century Portuguese shipwrecks

Raman spectra were recorded of the various components of a series of about 20 ceramic shards from nine Portuguese ships that were wrecked around the South African coast between 1550 and 1650. alpha-Quartz was a typical component of the porcelain body. The blue pigment could be identified as CoAl2O4, or cobalt blue, and the glaze covering the ceramic surface presented a series of broad Raman bands typical of amorphous silicates. One shard from the Santa Maria Madre de Deus, which looked different form the other shards, was shown not to be a porcelain owing to the various components (CaCO3, CaSO4.2H(2)O or gypsum, amorphous carbon, anatase) which could be identified in the ceramic. This is an indication that this one piece is unlikely to be of the same Chinese origin as the Ming porcelain shards. Copyright (C) 2004 John Wiley Sons, Ltd.