Gonnardite | |
---|---|
![]() 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.
{{cite web}}
: CS1 maint: archived copy as title (link)