Natrolite

Natrolite
General
CategoryTectosilicate
Formula
(repeating unit)
Na2Al2Si3O10·2H2O
IMA symbolNtr[1]
Strunz classification9.GA.05 (10 ed)
8/J.21-10 (8 ed)
Dana classification77.01.05.01
Crystal systemOrthorhombic
Crystal classPyramidal (mm2)
H–M symbol: (mm2)
Space groupFdd2
Unit cella = 18.27, b = 18.587
c = 6.56 [Å], Z = 8
Identification
Formula mass380.22 g/mol
ColorWhite, colorless, sometimes pink
Crystal habitAcicular
TwinningOn {110}, {011}, {031}
CleavagePerfect on {110}
FractureIrregular, uneven
TenacityBrittle
Mohs scale hardness5–6
LusterVitreous, silky, pearly
StreakWhite
DiaphaneityTransparent to translucent
Specific gravity2.25
References[2][3][4]

Natrolite is a tectosilicate mineral species belonging to the zeolite group. It is a hydrated sodium and aluminium silicate with the formula Na2Al2Si3O10·2H2O.[4] The type locality is Hohentwiel, Hegau, Germany.[3]

It was named natrolite by Martin Heinrich Klaproth in 1803.[3] The name is derived from natron (νατρών), the Greek word for soda, in reference to the sodium content, and lithos (λίθος), meaning stone. Needle stone or needle-zeolite are other informal names, alluding to the common acicular habit of the crystals, which are often very slender and are aggregated in divergent tufts. The crystals are frequently epitaxial overgrowths of natrolite, mesolite, and gonnardite in various orders.[2]

  1. ^ Warr, L. N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ a b R. Tschernich, Zeolites of the World, Geoscience Press, 1992.
  3. ^ a b c M. H. Klapoth, XV. Chemische Untersuchung des Natroliths, Ges Naturforsch Freunde Berlin Neue Schriften, V 4, pp 243-248, 1803.
  4. ^ a b D. S. Coombs, Recommended Nomenclature for Zeolite Minerals: Report of the Subcommittee on Zeolites of the International Mineralogical Association, Commission on New Minerals and Mineral Names, The Canadian Mineralogist, Vol. 35, pp. 1571-1606, 1997. [1]