Hundreds of semi-precious stones of immeasurable value are hidden in the Archbishop's Castle in Kroměříž. The unique discovery was made by Jana Zapletalová – a researcher from Palacký University Olomouc (UP) while examining the stucco decorations in the castle. Amethysts adorn the so-called grottoes, or artificial caves.
The Archbishop's Castle in Kroměříž was built and decorated at the end of the 17th century on the orders of Karl of Liechtenstein-Castelcorn, Bishop of Olomouc. Thanks to its significance and artistic qualities, the castle is listed as a UNESCO World Heritage Site. However, no one knew that it concealed a treasure in the form of hundreds of amethysts and other minerals, which decorated both grottoes – artificial caves built at the end of the 17th century in the basement of the castle.
During her scientific work on the rich stucco decoration of the castle's ground-floor halls (sala terrena, pl. salae terrenae), art historian Jana Zapletalová noticed that the cave glistened unusually in some places. “It was early January, and my colleagues had been collecting stucco samples for laboratory analysis for several hours. Only two people could work on the scaffolding, so I started to examine the adjacent darkened grottoes in detail with a flashlight. When I climbed behind the statue of Apollo, which dominates one of the two caves, I noticed sparkling reflections. At that moment, I realized that amethysts were almost everywhere under the layers of deposits,” said Associate Professor Jana Zapletalová, head of the Department of Art History at the Faculty of Arts, UP, describing the moment of discovery.
Artificial caves designed to imitate nature were very popular among the European aristocracy during the Baroque period. Thanks to water features and low temperatures, they served as a place for summer refreshment and entertainment, and their imaginative artistic decoration usually concealed some allegorical message. According to Jana Zapletalová, the decoration with precious stones in both Kroměříž grottoes is unique in the world. Amethysts, along with other minerals and shells, are not only part of the walls and vaults, but are also set into the floor of the Mining Grotto. The unique decoration was commissioned on the orders of Karel of Liechtenstein-Castelcorn, Bishop of Olomouc, who was the builder of the Kroměříž castle and gardens. However, he himself never enjoyed the grottoes in their full splendour, as he died shortly after their completion in 1695.
Amethysts were the most decorative part of Apollo's grotto, immediately surrounding the statue of the sun god, who allegorically personified Bishop Karl himself. “In various prints, the Bishop was associated with a shining stone or sun, bringing spiritual and economic renewal to Moravia with the rays of his faith and knowledge. The reference to light symbolism came from the Bishop's family name, Liechtenstein, meaning ‘light’ or ‘shining stone’, which was also featured in the family coat of arms. That is why there is a dazzling glow of amethysts around the statue of the sun god, who threw an arrow, i.e., a ray of light and faith, into the dark part of the grotto with a dragon, full of fauns, wild animals, and oak trees,” added Zapletalová.
The amethysts discovered in the Kroměříž Castle are of domestic origin. According to geologist Radek Hanus, who specializes in the research of precious stones in the Czech Republic and who performed a mineralogical analysis, they come from Květnice hill near Tišnov. Historical sources also reveal that they were transported to the site in beer barrels.
Most of the amethysts were lost from the castle in the past, especially the amethyst wall behind the statue of Apollo. “Whether this was the reason why the rest of the stones were covered with a layer of mortar, and thus hidden from the public and experts alike, is still unclear, as is the time when the concealment took place. In the 1950s, the walls were also covered with layers of paint by students from the Secondary School of Applied Arts in Uherské Hradiště,” added Associate Professor Zapletalová.
“The main goal of the Archbishopric of Olomouc is now to ensure the restoration of the monument so that these exceptional spaces, currently in a state of disrepair, can be preserved for the future. Since the discovery, we have worked with a number of specialists to carry out mineralogical analysis, archival and art-historical research, radiographic examination of the stucco decorations, assessment of the grottoes' structural stability, preliminary restoration surveys, climate monitoring, dehumidification of the premises, and high-resolution 3D scanning, which was provided by G4D,” said Alena Tobolková, head of the Archbishopric's Heritage Conservation Department, who manages and coordinates all the work and research.
“Further research and restoration work will now take place, which will last for a number of years. It will be necessary to involve foreign experts and obtain funding for such a demanding process,” added Alena Tobolková. However, even during the study and restoration work, the grottoes will remain partially accessible to visitors thanks to protective floor coverings and grotto viewpoints, which will allow the public to enjoy at least partial tours under safety measures.
