Slovak gemstones

In present-day Slovakia the survey in gemology has been oriented to searching for new gemstone deposits and to proving their quality. Suitable kinds of siliceous materials, which have not been examined for these purposes until now, have been discovered. Obsidians were found in eastern Slovakia, with their qualities predetermining them for use as chipped stone implements far in the past. In addition to sharp chipped edges that were used to function as various cutting implements, obsidians are attracting our attention by their black colour and remarkable lustre. Also in the present obsidian lumps of different size can be found on clayey
sediments in vineyards at the position of Viničky. Interesting remains of trunks of Tertiary trees, which were devastated by volcanic activities, are known as wood opals. One part of their wooden mass burned; the other was buried in volcanic ash and gradually impregnated with opal mass to give rise to attractive colourful remains with characteristic structure of original woods - chestnut trees, laurel trees and other thermophilous plants as well. Polished opals have impressive appearance and like obsidians, they can be used for jewellery. When set in jewels, their banded structure becomes apparent in play of colours. This quality is specific with embossed cuts. The site of Veľký Ďur-Rohožnica is a typical deposit. Wood opals from Povrazník are those with nice colours. They are of brown, orange, orange-red colours and have bright glassy lustre. Wood opals occur in positions of pyroclastic rocks of stratovolcanos. Common opals occur at several places in Slovakia as well, often accompanying wood opals and chloropals. They have glassy to dull lustre and different colour variations. Rather big accumulations were unearthed e.g. near Mochovce (Dobrica) in vein fillings of andesite rocks. Another type of opal is the one from the crust of a weathering ultrabasic body near Hodkovce, eastern Slovakia. It also occurs in a variety of colour variations, from light yellow to green (colouring due to Ni mixtures.
   Attractive stuff for cabochon cuts and minute embossed cuts are fuchsites or fuchsitic quartzes (occurring at Rudňany). They make altered rims of ultrabasic bodies and at some placed they are rather thick. Their negative feature is that they have been secondarily fractured to a high degree.
   Fractions of exclusive high-quality epidotites are suitable for decorative purposes as well. They are vein fillings in granitoid rocks of the Tríbeč hills. Epidote veinlets are solid and massive and they can be as thick as several centimetres. Interesting pebbles can be found in alluvia of brooks crossing the mountain range. Being cut and polished, initially modest boulders obtain attractive structure and lustre. The Levice travertine, known as “golden onyx” for its remarkable colouring and banded structure, has been used for decades traditionally. First it was used for interior facing of noble mansions and burial vaults. Later utility artefacts, such as bowls and writing sets were made of it. In present tiny gemstones and accessories are made of its waste.