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Gwindel

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Formula:
SiO2
Name:
From German "Gwindel", meaning "gewunden" = contorted, twisted, wound. Pronounced "gvin-dell".
A variety of Quartz

Quartz crystals that grew along and are slightly rotated around a single a-axis. This results in twisted and tabular crystals. The twist reflects the handedness of the quartz crystals. With increasing distance from the base
- right-handed gwindels twist clockwise.
- left-handed gwindels twist counter-clockwise.
In most gwindels the handedness can easily be determined by the position of the trapezohedral "x"-faces.

Gwindels are found in alpine-type fissures and are always accompanied by macromosaic quartz of normal habit. They are often smoky, rock crystal gwindels are less common.

The structural base of the twist has just recently been discovered: A high number of straight screw dislocations cause a uniform so-called Eshelby twist (Cordier and Heidelbach, 2013; Eshelby, 1953) that is typical for slow growing crystals. This slow growth is in line with the occurrence of gwindels in certain alpine-type fissures.

Because of the often multiple tips and the strong development of sutures on the crystal surface, gwindels are often described as lateral stacks of quartz crystals. This is not correct: each gwindel starts as a single crystal, and only the overgrowth with quartz of a macromosaic structure causes the impression of a composite specimen (Kuzmina et al, 1987; Dolino and Bastie, 2009).

Note: Gwindel-type growth is also known for other minerals.



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Pronounciation of GwindelHide

Pronounciation:
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Jolyon & Katya RalphUnited Kingdom

Chemical Properties of GwindelHide

Formula:
SiO2

Synonyms of GwindelHide

Other Language Names for GwindelHide

Common AssociatesHide

Associated Minerals Based on Photo Data:
Chlorite Group2 photos of Gwindel associated with Chlorite Group on mindat.org.
Smoky Quartz1 photo of Gwindel associated with Smoky Quartz on mindat.org.
Adularia1 photo of Gwindel associated with Adularia on mindat.org.
Quartz1 photo of Gwindel associated with Quartz on mindat.org.

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for GwindelHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Tschermak, G. (1894) Über gewündene Bergkrystalle. Denkschrift der Akademie der Wissenschaften, Mathematisch-Naturwissenschaftliche Classe: 61: 365-400.
Eshelby, J.D. (1953) Screw dislocations in thin rods. Journal of Applied Physics: 24: 176-179.
Kuzmina, M.A., Punin, Y.O, Kamentsev, I.E. (1987) Diagnostic features of the external and internal morphology of the screwed quartz crystals. Proceedings of the Russian Mineralogical Society: 116: 445-453.
Žorž, M. (1994) Pyroelectrically caused twisting of quartz crystals. In Geologija: 35th book: 183-206.
Moore, T.P. (2007) Alpine quartz gwindels. Mineralogical Record: 38: 103-121.
Dolino, G., Bastie, P. (2009) X-ray study of twisted natural quartz (gwindels).
ESRF Report, MA-507, Laboratoire de Spectrometrie Physique, Universite Joseph Fourier, Grenoble.
Žorž, M. (2009) Quarz-Gwindel. Mineralien-Welt: 20(3): 30-46.
Cordier, P., Heidelbach, F. (2013) Origin of twist in "gwindel" quartz crystals from the Alps: a transmission electron microscopy study. European Journal of Mineralogy: 25: 145-153.

Internet Links for GwindelHide

Localities for GwindelHide

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
France
 
  • Auvergne-Rhône-Alpes
    • Haute-Savoie
      • Chamonix
        • Mont Blanc Massif (Monte Bianco Massif)
Hède frédéric
Van King
Hède frédéric
Namibia
 
  • Hardap Region
    • Rehoboth District
Niedermayr, G. & Schnaitmann, E. A. (2010): Neuigkeiten aus Namiba. Mineralien-Welt 21 (6), 89-96.
Switzerland
 
  • Bern
    • Hasli Valley
      • Grimsel area
        • Oberaar lake area
          • Oberaar glacier
Teige, B., Willener, A. (1997) Die Gwindelkluft an der Oberaar (BE) oder wenn Strahler strahlen. Schweizer Strahler, 10(11).
  • Grischun (Grisons; Graubünden)
    • Vorderrhein Valley
      • Russein Valley
        • Cavardiras Valley
Photo ID: 432242
      • Tujetsch (Tavetsch)
        • Curnera Valley
Yaiba Sakaguchi
Koenigsberger, J.G. (1940) Die zentralalpinen Minerallagerstätten, Wepf und Co. Verlag, Basel.
  • Wallis (Valais)
    • Le Trient Valley
Frederic Hede
Mineral and/or Locality  
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