Twisted fibrous magnesian calcite in carbonate rocks of the Russian Platform

Twisted crystals represent a specific and relatively rare form of many mineral species, such as gypsum, chrysotile and amphibole asbestos, tourmaline, zeolites, chalcedony, millerite, boulangerite, malachite, hypergene iron sulfates, ice, and rock salt. Maleev reported tiny fibrous calcite crystallites from limestone caves in Bulgaria. Seemann and Fischer investigated the so-called mondmilch (montmilch, bergmilch) composed of friable straight fibrous calcite crystallites (approximately 0.1 m thick and up to 100 200 m long) in limestone caves in the Hhle area near Lucerne (Switzerland). During detailed engineering-geological investigation of carbonate rocks in Zaryadye (Moscow), T.T. Abramova detected fibrous carbonate segregations.