Trial of the Pyx

The Trial of the Pyx (/pɪks/) is the procedure in the United Kingdom for ensuring that newly minted coins conform to the required standards. These trials have been held from the twelfth century to the present day, normally once per calendar year.

The form of the ceremony has been essentially the same since 1282 AD. These events are trials in the full judicial sense, presided over by a judge with an expert jury of metallurgical assayers. Given modern production methods, it is unlikely that coins would not conform, but this has been a problem in the past—it was tempting for the Master of the Mint to steal the coins' precious metals.

Trials are now held at the Hall of the Worshipful Company of Goldsmiths; formerly, they took place at the Palace of Westminster. There is also a Pyx Chapel (or Pyx Chamber) in Westminster Abbey, which was once used as secure storage for the Pyx and related articles.

The term "pyx" refers to the boxwood chest (in Greek, πυξίς, pyxis) in which coins were placed for presentation to the jury.

In medieval times the Master of the Mint was ordered to save for trial one coin for every ten pounds of silver minted. A trial was normally conducted every three months.

The presiding judge is the Queen's Remembrancer (or King's Remembrancer when the sitting monarch is male), the Senior Master of the Queen's Bench. It is his or her responsibility to ensure that the trial be held in accordance with the law and to deliver the jury's final verdict to Her Majesty's Treasury. Where and when a trial is to take place is at the Treasury's discretion, though there must be a trial in any year during which the Royal Mint issues coins.

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