Mineralogical occurrences of precious opal are relatively common. But commercially mineable accumulations (deposits) are known only from a few places. Červenica-Dubník is one of them.
Precious opal in the locality drew attention of many
illegal diggers as well as legal entrepreneurs contracted with the state, who became forever an inseparable part of a remarkable story.
Mining of the gems at Dubník was very difficult
because they occur there extremely irregularly. When they finally came to the light, they had to be extracted with the highest circumspection.