The Trial of Pyx: Testing the purity of gold

Blog

By Alison Cook, Operations Manager

I am fascinated by gold and anything to do with the subject. A few years ago I heard about one of the more obscure practices associated with gold coins in this country – the Trial of Pyx.

But before we become too pyxated, let me explain some of the historical context.

Historically, the earliest English coins were made of silver and occasionally gold. The Royal Mint was established in 886 under Alfred the Great (848-899), more than 1,100 years ago. It wasn’t until 1270 that it centralised control of various smaller, local mints at the Tower of London, an ultra-secure location which was the home of the Royal Mint for the next 500 years.

Shortly after moving to the Tower, it was recognised that some kind of quality control process was needed and the Trial of Pyx was introduced in 1282. The purpose of the Trial was, and continues to be, to independently assess the quality and consistency of the coins produced by the Royal Mint.

The Trial of Pyx takes its name from the box in which sample coins were put aside for subsequent testing. Historically, a pyx or pix was a small round container used for carrying the Eucharist to the sick, or others, unable to take Holy Communion in church.

Today, the pyx is the box in which specimen gold and silver coins are deposited to be tested at the annual Trial held by Goldsmiths' Company. The coins represent one piece for every batch of each denomination produced by the Royal Mint.

Early Trials were held in Westminster Hall and then at the Exchequer in Westminster. The 1870 Coinage Act specified that the venue for the Trial be the Hall of the Worshipful Company of Goldsmiths. This is also the location of The Goldsmiths' Company Assay Office, which is tasked with testing the metallic composition of coins.

The Goldsmiths' Company is one of London's oldest livery companies, founded in 1327. Livery companies are guilds or professional associations, so called because of the uniforms or regalia that members wore, and which allowed them to be readily identified.

The other participants in the Trial are the Royal Mint (who produce the coins) and the Government, represented by the Chancellor of the Exchequer, who is also known as the "Master of the Mint".

The Trial is opened by the senior judge of the Royal Courts of Justice, known as the King's Remembrancer. The jurors randomly select coins from the Pyx packets which are then weighed, measured and tested to ensure that the composition of the metal meets the expected standards.

If not satisfied with what they find, the jury has powers to take action against the Master of the Mint. The Chancellor can be fined, struck off or even imprisoned. The last Master to be sanctioned was Sir Isaac Newton in 1710. 

Newton became Warden of the Mint in 1696 and moved to the more junior, but significantly more lucrative, post of Master in 1699. Although the Trial of Pyx in 1710 judged that his gold coins were below standard, this was subsequently proven to be mistaken. So it would be fair to say that Isaac Newton’s reputation remains untarnished.