An Introduction to the Metals from the Mary Rose by Keith Watson

The references in the text are to Volumes 1-5 of The Archaeology of the Mary Rose (AMR) published by the Mary Rose Trust Ltd.

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1. Introduction

The Mary Rose sank on the 19th July 1545. Many of the objects that she carried to the bottom of the sea were made of metal. These range from gold coins to the massive guns, some made of bronze and some of iron. This discussion is aimed at the non-specialist reader and introduces the various metals – and some of the objects made from them – that were recovered from the Mary Rose. It provides an elementary account of how they corroded on the seabed and how they have been conserved. But first we need to have a simple concept of what metals are and how they behave.

2. The Nature of Metals

Metals - like all other materials - are made of atoms, which are extremely small. For instance, a straight row of four million copper atoms is only just over a millimetre long.

An atom consists of a tiny positively charged nucleus surrounded by a negative electron cloud. The nucleus contains particles called protons, which carry the positive charge, and neutrons, which are electrically neutral. Each element is distinguished from all the others by the number of protons in its nucleus; for instance one in hydrogen, eight in oxygen, twenty six in iron and seventy nine in gold. The negative cloud consists of particles called electrons, each of which carries an equal and opposite charge to the proton. This means that a neutral atom contains equal numbers of electrons and protons.