Gottardiite, a new high-silica zeolite from Antarctica: the natural counterpart of synthetic NU-87
Galli, Ermanno; Quartieri, Simona; Vezzalini, Giovanna; Alberti, Alberto
European Journal of Mineralogy Volume 8 Number 4 (1996), p. 687 - 694
published: Jul 29, 1996
manuscript accepted: Feb 21, 1996
manuscript received: Aug 31, 1995
ArtNo. ESP147050804004, Price: 29.00 €
Abstract Gottardiite has been discovered in the Jurassic Ferrar dolerites of Mt. Adamson (Northern Victoria Land, Antarctica). The new zeolite occurs as subparallel aggregates of transparent pseudo-hexagonal lamellae. The mineral is orthorhombic, space group Cmca, with a = 13.698(2), b = 25.213(3) and c = 22.660(2) Å. The strongest X-ray diffraction lines are (in Å): 11.34(100), 4.37(79), 4.01(57), 3.282(68). The gottardiite framework topology is the same as that of synthetic NU-87. The chemical formula is: Na2.5K0.2Mg3.1Ca4.8 Al18.8Si117.2O272·93H2O. The Si/Al ratio is 6.2, the highest found up to now in a natural zeolite. Gottardiite is optically biaxial (-), with α = 1.480(2), ß = 1.485(2), γ = 1.486(2), 2V < 60º, where X = b, Y = a and Z = c. The density is 2.14(4)g/cm3 (obs.), and 2.16 g/cm3 (calc). Both thermal stability and rehydration capacity are very high. The name is in honour of Glauco Gottardi (1928-1988).