natrolite

{{Infobox mineral | name = Natrolite | boxwidth = | boxbgcolor = | image = Natroliteinde1.jpg | imagesize = 260px | alt = | caption = | category = Tectosilicate minerals | group = Zeolite group, natrolite subgroup | formula = | IMAsymbol = Ntr | molweight = 380.22 g/mol | strunz = 9.GA.05 (10 ed) 8/J.21-10 (8 ed) | dana = 77.01.05.01 | system = Orthorhombic | class = Pyramidal (mm2) H–M symbol: (mm2) | symmetry = Fdd2 | unit cell = a = 18.27, b = 18.587 c = 6.56 [Å], Z = 8 | color = White, colorless, sometimes pink | colour = | habit = Acicular | twinning = On {110}, {011}, {031} | cleavage = Perfect on {110} | fracture = Irregular, uneven | tenacity = Brittle | mohs = 5–6 | luster = Vitreous, silky, pearly | streak = White | diaphaneity = Transparent to translucent | gravity = 2.25 | density = | polish = | opticalprop = | refractive = | birefringence = | pleochroism = | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | prop1 = | prop1text = | references = }}

Natrolite is a tectosilicate mineral species belonging to the zeolite group. It is a hydrated sodium and aluminium silicate with the formula . The type locality is Hohentwiel, Hegau, Germany.