Leucophyllite

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Leucophyllite, 16 × 13 cm

Leukophyllites (from ancient Greek λευκός leukós , German 'white' and φύλλον phýllon , German 'sheet' - literally "white sheet") are a group of bright, bleached phyllites of different composition that arise from hydrothermal metasomatosis . The name is derived from the white, glossy and thin-leaved appearance.

History of exploration

Leucophyllite , also called pycnophyllite , is a mixture of chlorite , sericite and talc . The name goes back to G. Starkl, who named the mineral mixture because of its white, leafy appearance and regarded it as a separate mineral. As a result, leukophyllite was viewed as the silicate-rich end member of the muscovite mixed series before its nature as a mixture was recognized. The name has been extended to white, bleached rocks since the first description.

Demarcation

It is not a matter of rocks with a uniform composition, but of transformation products that have arisen from phyllitization and bleaching of various original rocks. The naming is not uniform, one finds leukophyllite , white slate , cornstone or muscovite quartzite . In addition, leukophyllite is a trade name for quartz-muscovite-chlorite rocks regardless of their origin.

The leukophyllites are not to be confused with the real white slate , a rare metamorphic rock that is formed under high pressure and high temperatures.

properties

Leucophyllites are light-colored, fine schistous rocks that consist of a mixture of quartz and muscovite and contain chlorite, disthene , apatite and zirconium . The quartz can be contained in small spheres several millimeters in diameter.

Economical meaning

Leukophyllites are used in the paint and varnish industry as rust protection and opacity enhancers, to facilitate distribution and improve weather resistance.

literature

  • W. Prochaska: Talc and leukophyllite formation as a consequence of hydrothermal metasomatosis . In: Communications of the Austrian Geological Society . tape 78 , 1985, pp. 167–179 ( online [PDF; 720 kB ]).
  • G. Starkl: About new mineral occurrences in Austria . In: Yearbook of the Geological Reich Institute . tape 23 , 1883, p. 635-658 .

Individual evidence

  1. ↑ data sheet Leucophyllite . (English)
  2. ^ WM Heinrich: Natural Mica Studies, Quaterly Report. Engineering Research Institute, University of Michigan, Ann Arbor, 1952, accessed December 17, 2009 .
  3. ↑ Prochaska 1985, p. 168
  4. ↑ New mine opened. ORF Styria, September 29, 2006
  5. ↑ Paints and Varnishes - IMERYS Talc Austria. Retrieved December 6, 2019 .