European Opal or .. Opal in Slovakia

A little introduction to this occurrence of precious opal is needed. Precious opal from this occurrence in Europe is most likely the oldest known source for the production of the gem. Different records in literature can often detail geographically different names of localities with different emphasis. An attempt will be made to elucidate these differences so that it will become apparent that the records are of the same opal fields in each case. It is also interesting to note that various places named which are associated with European opal have been “anglicised”, or if I may “americafied”. Peter Semrád allays all of these issues in his book: “The story of European Precious opal from Dubnik” 2011. ISBN: 978-80-7296-079-8.

I am indebted to my colleague Peter Semrád who has produced numerous pieces of literature regarding what he now calls “European Opal”. These will be highlighted in the literature section of the library. Peter Semrad’s description of both the History and the geography of the area should allow readers to unite all the details covered in literature.

A LITTLE HISTORY

Frank Leechman (1961) writes of this occurrence saying:

“These mines, 2000 years old, although unknown to the Romans, formed their (the Romans) source of supply. Besides the chief area which is near Presov (Eperias), opal occurs east of Kashau (Kosice) at Nagy-Mihaly on the Laborcza River.”

“The workings near Czerwenitza are said to be by “Bauer” to be fifteen miles (about 25 kilometres) to the south-east of Eperias (Presov). At the foot of Simonka, the highest mountain of a wild forest region, is the small settlement of Dubnik which owes its existence to the occurrence of opal in that region.”

Peter Semrád (2011) writes of the history of this occurrence saying:

“Probably the oldest written indication of mineral resources within the Lipovec manor, (i.e. the historical area which comprised the locality of the later opal mines, is dated as early as 1299…..” However opal is not documented in this resource.

“Another preserved document dated 27th October 1568, describes mining in the area”….But again this document does not mention opal.

“Due to the lack of evidence we cannot say accurately what happened during the next three decades, but it is obvious that to hush up the occurrence of precious opal in the Dubnik was becoming more and more difficult.”

“Finally the truth came out and in a short time the news about the colourful stones reached the ears of Emperor Rudolf the second…….

According to Semrád the emperor owned a collection of precious opals from Dubnik, and as mineralogy was amongst some of the emperor’s interests, he issued a decree to look for opal within the entire Kingdom of Hungary.

You can read the rest of the history in the already mentioned text on European opal.

GEOGRAPHY AND MINING FIELDS

Peter Semrád writes in the introduction:

“If you really want to become personally acquainted with the historical locality of the long-ago mined deposits of precious opal in Europe, you have to strike out for Eastern Slovakia, and once there – either from Košice via Červenica (old Hungarian: Vörösvágás), or from Prešov via Zlatá Baňa ( old Hungarian Aranbánya), possibly from Vranov and Topľou via Zámutov ( old Hungarian; Opálhegy) – directly into the northern part of the Slanské vrchy Mountains. However, it is only if you reach the more or less defunct mining centre of Dubnik (old Hungarian Opálbánya), located at the geometric centre of an imaginary geographical triangle defined by the villages of Červenica, Zlatá Baňa and Zámutov, can you be sure that you are in the very place!”

You can read the introduction in the literature section of the Opal Academy.

The above map shows the position of the opal mining areas in the Slanské vrchy Mountains and in the Zlatá Baňa stratovolcano, from Peter Semrád.

OTHER LITERATURE

The Story of European Precious Opal from Dubnik - 2011 - Peter Semrad

Structure of Precious opal from Cervenica - 1980 - Dodony, I and Takacs, J.

Opals from Slovakia (“Hungarian” opals): a re-assessment of the conditions of formation. - 2004 - Benjamin Rondeau, et al. - European Journal of Mineralogy, Vol 16, 789-799.

A LITTLE GEOLOGY

The precious opal deposits in this region occur in area that is built up from volcanism which occurred in the Neogene period of the geological time scale, some 2.5 to 23 million years ago. Studies of the rocks in the area support a postulated age of 10 to 11 ma for the emplacement. The opal deposits are situated in the southern part of the Zlata Bana stratovolcano. The main rock type is an andesite of lava-clastic type believed to be erupted in Samartian age. Opal also occurs in the area of Simonka and the Libanka Hills which are separated by breccia zones. The opal is concentrated in tectonic zones that have a NW-SE direction and widths of 10 - 80 metres which are 1.1 kilometres long. The opal is present in these zones in the form of irregular veinlets, fillings of interstices and pores in the andesite, however it is also known in the form of cement in brecciated andesites as a form of matrix opal.