Topaz quartzolite (greisen) in North Bohemia – potential source of the natural abrasive

Topazolite (greisen) is a rock formed essential by quartz and topaz, with accessory white mica, tourmaline, sulphides (molybdenite and arsenopyrite), wolframite and cassiterite. This rock was found in the Krkonoše and Jizera Mountains in the western Sudetes. In Poland, this metasomatic rock occurs at the contact between leucogranite and mica schist (associated with hydrothermal kaolinization) in a narrow zone between the settlements of Rebiszow and Gierałtówek. On Czech territory, similar topaz quartzolite (greisen rock), consisting of up to 65 % quartz and 32 % topaz, was found near the settlements of Růžek and Vítkov near Chrastava in association with orthogneiss. The high content of topaz in this rock offers the possibility of using it as an abrasive in high-speed abrasive water jet technology for cutting and surface treatment of hard metallic and non-metallic materials. In the crushed form, after being concentrated in a treatment plant, topaz could be a natural abrasive with a wide range of applications. However, the results of technological testing of the physical and mineralogical characteristics of the topaz concentrate indicate its unfavorable properties caused by the high fissility of topaz. This leads to losses of topaz during its technological adjustment to the required grain size or during recycling. It has been shown that abrasive concentrates with topaz content above 90 % are promising, especially for special applications of abrasive water jet technology. Mastering the technology for processing of the source raw material, i.e. topaz quartzolite, into a topaz-rich concentrate, and subsequent applied research on the use of topaz abrasives in industry are crucial.