Chemical and mineralogical study of a Yamur from the Thirteen Century

Abstract

The aims of this research were the chemical and mineralogical study of a Yamur from the thirteen Century and the study of their conservation degree in order to facilitate the restoration. The Yamur was located in the upper part of the dome of the Conceptionists Convent in Los Pedroches (Cordoba, Spain). The restoration project was carrying out in the Andalusian Institute of Cultural Heritage (IAPH), according to the silver restoration protocol under the commission of the Andalusian Culture Ministry. The Characterization was carry out by Optical Microscopy (OM), X-ray Diffraction (XRD), Inductively Coupled Plasma (ICP) and Scanning Electron Microscopy coupled to energy dispersive X-ray spectroscopy (SEM-EDX). The spheres are made of brass (copper and zinc alloy) with mi nor proportion of lead. This composition decreases the melting point and allowes the work of the piece. The sphere brass corrosion is due to the presence of cuprite and paramelaconite while the illite found in the deposits could have a soil origin.