It is a rectangular box made of wood of
European Pear, with a lid in the shape of a truncated pyramid. The
Agate box is long, wide and high. The wooden box is covered with sheets of gold forming unequal arches in which 99 large flat sections of veined
agate are mounted. The gold is decorated with
cabochon gemstones and
coral. The top of the lid is a gold plaque with a cross and three large gems which was taken from an older piece. It is decorated with small animals in
enamel in a kind of
champlevé technique that is only found in one other work, the South German rear cover of the
Lindau Gospels, of the late 8th century, now in the
Morgan Library, New York. The base of the box is made of pure silver, with a cross made of
gems and with a carved
tetramorph, representing the four evangelists: the angel of
St. Matthew, the Lion of
St. Mark, the ox of
St. Luke and the eagle of
St. John. The inscription which describes the donation of the box to the cathedral is engraved on the basex. It reads: == Notes ==