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Download hereGENERAL DESCRIPTION
Natrolite is a hydrated sodium aluminosilicate, belonging to the family of zeolites. It is the most common of the fibrous zeolites. Natrolite is formed in cavities within the eruptive rocks (mainly basalts) but also in weathered basic rocks (such as serpentines).
Natrolite can be associated other minerals such as mesolite or apophyllite. Its crystals are lengthened and pseudo-quadratic. They often form acicular clusters. Natrolite is white in color, with a pearly lustre.
Natrolite is found in many despoits worldwide: district of Poonah in India (from or the most beautiful groups are coming from), Kolskiy in Russia (crystals of more than 40 cm in length), Mont Saint-Hilaire and Nova Scotia in Canada, New Jersey (USA), Australia, Portugal...
In France, the Puy de Marmant (Puy De Dôme) is the most known deposit but natrolite is also found in various surrounding localities like in Aveyron, close to Espalion and Rodez and in Alba (Coirons, Ardèche).
The place of conservation of the type of this species (originating from the Hohentwiel Mts, Singen, Hegau, Bade-Württemberg, Germany) is not known.
Did you know? To differentiate natrolite, scolecite from mesolite, one must precisely know the chemical composition. The first is sodic, the second is calcic and the third is sodo-calcic.
HISTORY : Name derived from Greek "νατρον" [natron] meaning "soda" and "λιτὁσ" [lithos] meaning "stone"
Species described in 1803 by Martin Heinrich Klaproth (1743-1817), Germand professor of chemistry in the Berlin University
Type-locality : Hohentwiel, Germany
CHEMICAL FORMULA : Na2 [Al2 Si3 O10] 2H2O
CRYSTAL SYSTEM : Orthorhombic
COLOR : White, colorless, red, yellow, brown
DIAPHANIETY : Transparent to translucent
LUSTER : Vitreous, pearly
STREAK : White
MORPHOLOGIE : Prismatic crystals
HARDNESS : 5,0-5,5
CHEMICAL CLASS: 2,25
DENSITY : VIII - Silicates
GROUP : Natrolite
STRUNZ CLASS BEFORE 2001 : 8/J.21-10
STRUNZ CLASS AFTER 2001 : 9.GA.05
