SLOVAK OPAL by Costantini

The publication is an attempt to deal out historical justice to the Slovak opal and to present its long-time journey.

In individual chapters, the Italian author Luigi Costantini explains the genesis of opals in the Old Continent, dealing in detail with the oldest opal mines in the world – mines in the locality of Dubník, Slanské vrchy in the Eastern Slovakia. In reading, follow the author down to the opal mines, see the work of the miners, digging and processing opals in the past, and learn about reasons to stop the extraction in the last century.

The book also contains geological maps of the area as well as description of the deposit and detailed technical specification of Slovak opal.

Besides many other information, the author explains grading of Slovak opals and describes in detail the factors affecting its quality.