Mineral description : Natrolite

Natrolite from Långban, Värmland.

Mineral class Silicates : Tekto silicates : Zeolites
Chemical formula Na2Al2Si3O10*2H2O
Crystal system Orthorombic
Habitus As thin needlelike crystals in diverging or radiating groups, also as global, concentric shells, thready, derb, thick or mealy.
Cleavage Perfect, brittle.
Hardness 5-5.5
Density 2.2-2.26
Color Usually white to colorless, but nuances in yellow and pink.
Streak White.
Luster glas to pearly, silky on fibrous variants.
Occurance Usually found in cavities in volcanic rocks, but also as a transformation product of nefeline and plagioklase.
Associates Other zeolites, calcite.
Similar minerals Mesolite, scolesite.
Notes Soluble in strong acids. Yellow staining of a flame.
Locations A rare mineral in Sweden.

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Last changed : 1998-03-07