Slates

Roof and wall slates are fine-grained rocks with slaty cleavage, and it is often difficult to determine their mineral composition. A new norm mineral calculation called slatecalculation allows the determination of a virtual mineral composition based on full chemical analysis, including the amounts of carbon dioxide (CO2), carbon (C), and sulfur (S). Derived norm minerals include feldspars, carbonates, micas, hydro-micas, chlorites, ore-minerals, and quartz. The mineral components of the slate are assessed with superior accuracy compared to the petrographic analysis based on the European Standard EN 12326. The inevitable methodical inaccuracies in the calculations are limited and transparent. In the present paper, slates, shales, and phyllites from worldwide occurrences were examined. This also gives an overview of the rocks used for discontinuous roofing and external cladding.

Slates, phyllites and schists from deposits of SW Poland used as dimension stones – evaluation of their deco-rativeness and the possibilities of use. Prz. Geol., 64: 833–843. A b s t r a c t. In modern architecture, slates, phyllites and schists are becoming more and more popular, and the example of Polish deposits of slates, phyllites and schists indicates that, in the last 10 years, the traditional method of using these rocks as raw material, e.g. for the production of granular surface, silty carriers of plant protection products or refractory material, has become gradually dominated by their use as dimension stones. The paper presents the first ranking of the decorative aspects, carried out for slates, phyllites and schists originating from active deposits: Or³owice, Jawornica, Dewon-Pokrzywna, Jeg³owa and Jenków, located in the Sudetic Block and Fore-Sudetic Block (Lower Silesian Block, SW Poland). Evaluation of the decorative aspects of slates, phyllites and schists, which takes into account the colour, textural and structural features of the rock, its ability to be polished, and pet-rologic type, revealed that the primary and secondary petrographic types documented in these deposits have a high decorative value, mainly because of attractive colour and structural arrangement of mineral components. It should be noted that in the group of over 150 different varieties of colourful metamorphic slates on the stone market in the European Union, Polish slates, phyllites and schists are characterised by unique colours. Therefore, the high decorative value and unique colours characteristic of the Polish slates, phyllites and schists is their essential trait that conditions their use as decorative stone material with a wide range of applications.