Gonnardite from the Bundoora Quarry, Victoria, Australia. Specimen size 4.9 cm
General
Category
Tectosilicate
Formula (repeating unit)
(Na,Ca)2(Si,Al)5O10·3H2O
IMA symbol
Gon[1]
Strunz classification
9.GA.05 (10 ed) 8/J.21-40 (8 ed)
Dana classification
77.1.5.7
Crystal system
Tetragonal
Crystal class
Scalenohedral (42m) H-M symbol: (4 2m)
Space group
I42d
Unit cell
a = 13.38 c = 6.66 [Å]; Z = 2
Identification
Color
Colorless, white, yellow or pink to salmon orange
Crystal habit
Radiating fibrous; massive
Mohs scale hardness
4 to 5
Luster
Vitreous to silky or dull
Streak
White
Diaphaneity
Translucent
Specific gravity
2.21 to 2.36
Optical properties
Biaxial (+)
Refractive index
nα = 1.514, nβ = 1.515, nγ = 1.520
Birefringence
δ = 0.006
2V angle
Measured, 52°
References
[2][3][4][5]
Gonnardite is a comparatively rare, fibrous zeolite, natrolite subgroup. Older papers claim that a complete solid solution exists between tetranatrolite and gonnardite, but tetranatrolite was discredited as a separate species in 1999.[6] A series, based on the disorder of the silicon-aluminum in the framework, appears to exist between Na-rich gonnardite and natrolite, Na2(Si3Al2)O10·2H2O.[7]
Gonnardite was named in 1896 after Ferdinand Pierre Joseph Gonnard[8] (1833–1923), who was Professor of Mining Engineering at the University of Lyon, France.
^Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C. (2005). "Gonnardite" (PDF). Handbook of Mineralogy. Mineral Data Publishing. Retrieved 13 March 2022.
^Gaines et al (1997) Dana's New Mineralogy, Wiley
^American Mineralogist (1999) 84: 1445–1450
^Tschernich, Zeolites of the World (1992) Geoscience Press, pages 215 to 225
^"Archived copy". Archived from the original on 2014-07-29. Retrieved 2010-03-30.{{cite web}}: CS1 maint: archived copy as title (link)
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