Gottardiite has been discovered in the Jurassic Ferrar dolentes 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. TheSi/Al ratio is 6.2, the highest found up to now in a natural zeolite. Gottardiite is optically biaxial (-), with α = 1.480(2), β = 1.485(2), γ = 1.486(2), 2V < 60°, where X = b, Y = a and Z = c. The density is 2.14(4)g/cm3 (obs.), and 2.16g/cm3 (calc.). Both thermal stability and rehydration capacity are very high. The name is in honour of Glauco Gottardi (1928-1988).
Gottardiite, a new high-silica zeolite from Antarctica
ALBERTI, Alberto
1996
Abstract
Gottardiite has been discovered in the Jurassic Ferrar dolentes 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. TheSi/Al ratio is 6.2, the highest found up to now in a natural zeolite. Gottardiite is optically biaxial (-), with α = 1.480(2), β = 1.485(2), γ = 1.486(2), 2V < 60°, where X = b, Y = a and Z = c. The density is 2.14(4)g/cm3 (obs.), and 2.16g/cm3 (calc.). Both thermal stability and rehydration capacity are very high. The name is in honour of Glauco Gottardi (1928-1988).I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
