Open AccessA tetragonal natrolite
Author(s) -
E. Krogh Andersen,
M Danø,
Ole V. Petersen,
M Mouritzen
Publication year - 1969
Publication title -
bulletin
Language(s) - English
Resource type - Journals
eISSN - 2597-2936
pISSN - 0105-3507
DOI - 10.34194/bullggu.v79.6619
Subject(s) - tetragonal crystal system , crystallography , mineral , chemistry , mineralogy , materials science , crystal structure , organic chemistry
Tetragonal natrolite has been found as white or, less frequently as, dull pink micro-crystalline aggregates in hydrothermal veins in naujaite, at two separate localities in Ilímaussaq. The aggregates are built up of sheaf-like groups of prismatic crystals, the greatest dimension of which is about 0.01 mm. The single crystals are bounded by a single prism and either a basal pinacoid or a bipyramid. The density is 2.210 ± 0.002. The mineral is uniaxial, optically positive. nε = 1.4093 ± 0.001, nα = 1.4080 ± 0.001. DTA and TOA curves of both ordinary natrolite and tetragonal natrolite are presented; tetragonal natrolite dehydrates at a slightly lower temperature than ordinary natrolite. The mineral is tetragonal, space group probably 142d. The unit cell dimensions are: a0 = 13.0403 ± 0.001 Å, C0 = 6.619 ± 0.001 Å, and Vol. = 2252 Å3. The chemical composition of the mineral falls within the range of composition of natrolites as reported in the literature.