Unverzweigte 18er Einfachring des Megacyclit Daten von: Zubkova N V., Pekov I V., Chukanov N V., Listsin D V., Rabadanov M K., Pushcharovsky D Y. (2007): New data on megacyclite, New Data on Minerals. Moscow, 42, pp. 81-92 http://rruff.geo.arizona.edu/AMS/download.php?id=17606.cif&down=cif Berechnung der Bilddaten: Larry W. Finger, Martin Kroeker, and Brian H. Toby, DRAWxtl, an open-source computer program to produce crystal-structure drawings, J. Applied Crystallography V40, pp. 188-192, 2007 http://www.lwfinger.net/drawxtl/ Rendering: POVRAY — Photo: Bubenik · CC BY-SA 3.0
Megacyclite
Megacyclite is an IMA-recognized mineral species in the silicate class, with the chemical formula KNa₈Si₉O₁₈(OH)₉·19H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/c).
Key properties: Mohs hardness 2; specific gravity 1.82; [White.] streak; Vitreous to subvitreous luster; optically biaxial.
IMA symbol Mgc, IMA status: approved, named in 1991.
Found in unweathered ultra-alkalic pegmatites in an alkalic massif.
It is found associated with Orthoclase, fenaksite, revdite, delhayelite, many other minerals.
Its name comes from the Greek for large and cyclical, with reference to the large ringlike groups of silica tetrahedra in the structure.