A trial of the pyx is mentioned in the Lansdowne MSS.
They are probably of the Norman period, and were kept in the Pyx Chapel at Westminster, now in the custody of the Commissioners of Works.
In the East it was kept against the wall behind the altar; in the West, in a locked aumbry in some part of the church, or (as in England and France) in a pyx made in the form of a dove and suspended over the altar.
In the English Mint the pyx is the chest in which are placed one coin from every 15 lb of newly coined gold and one from every 60 lb of newly coined silver to await the "trial of the pyx" (see Mint).
This chest was formerly kept in the Chapel of the Pyx in Westminster Abbey.
The chapel or chamber of the Pyx is part of the undercroft of the original dormitory, and is early Norman work of the Confessor's time.
It was used as a treasury for the regalia and other articles of value in early times, and here were kept the standard coins of the realm used in the trial of the pyx now carried out at the Mint.