Porcelain shards from Portuguese wrecks : Raman spectroscopic analysis of marine archaeological ceramics

Abstract

Raman spectroscopic analysis of shards recovered from two Portuguese shipwrecks, the Santo Espirito (1608) and the Santa Maria Madre de Deus (1643), believed to be carrying porcelains of the Ming period have revealed some interesting and novel results that inform historical ideas of porcelain production. The porcelain body of two of the four shards from the Santa Maria Madre de Deus were found to contain anatase, a low temperature polymorph of titanium dioxide, and β-wollastonite a mineral characteristic of soft-paste porcelains that are made at medium-temperature firing conditions. Previously, β-wollastonite has been found in a range of sixteenth to nineteenth century European porcelains but this is the first report of its detection in porcelain believed to be from the Ming period. These same shards exhibited unusual spectral features that were attributed to the resonance enhancement of rare earth elements that resulted from excitation using a near-infrared source.