Polishing slate
Polishing slate (also sticky slate , suction pebble , suction slate , silver triplet ) is a thin slate , very light, dull, light gray or yellowish-gray, also light yellow silicate rock , which rubs off, feels fine and lean, avidly absorbs water, i.e. sticks to the tongue, on the water floats (floating pebbles), but when soaked in water it has a specific weight of almost 2. In terms of its composition, the polishing slate corresponds completely to the kieselguhr , from which it only differs in its somewhat firmer texture and distinct foliation. Polishing slate is found as Limnian sediment , i.e. as a deposit in freshwater lakes of the tertiary period , in the Bohemian Central Mountains near Bilin , in the basalt tuff of the Habichtswald , also near Planitz , Ménilmontant , on Montmartre etc. It is used like triples for polishing and grinding metal, glass and other materials.
Individual evidence
- ↑ Polishing slate . In: Meyers Großes Konversations-Lexikon . 6th edition. Volume 16, Bibliographisches Institut, Leipzig / Vienna 1908, p. 97 .