mesolite

{{infobox mineral | name = Mesolite | category = Tectosilicate minerals | group = Zeolite group, natrolite subgroup | image = Mesolite from Bombay, Hunterian Museum, Glasgow.jpg | alt = | caption = Mesolite from Bombay collected in the 18th century by Dr John Hunter | formula = | IMAsymbol = Mes | strunz = 9.GA.05 | dana = | system = Orthorhombic | class = Pyramidal (mm2) (same H-M symbol) | symmetry = Fdd2 | unit cell = a = 18.4049(8) Å, b = 56.655(6) Å, c = 6.5443(4) Å; Z = 8 | color = Colorless, white, gray, yellowish brown | colour = | habit = As elongated prismatic crystals, commonly in hairlike tufts and aggregates of fibers; radiating compact masses; stalactitic; porcelaneous | twinning = Characteristically twinned on {010} or {100} | cleavage = Perfect on {110} and {10} | fracture = Uneven | tenacity = Brittle, masses tough | mohs = 5 | luster = Vitreous, silky when fibrous | streak = White | diaphaneity = Transparent to translucent, opaque | gravity = 2.26 | density = | polish = | opticalprop = Biaxial (+) | refractive = nα = 1.505 nβ = 1.505 nγ = 1.505 | birefringence = δ = 0.001 | pleochroism = | 2V = Measured: 80° | dispersion = | extinction = | length fast/slow = | fluorescence= | absorption = | melt = | fusibility = | diagnostic = | solubility = | other = May exhibit a small pyroelectric effect; piezoelectric | alteration = | references = }} Mesolite is a tectosilicate mineral with formula . It is a member of the zeolite group and the natrolite subgroup, also resembling natrolite in appearance.

Mesolite crystallizes in the orthorhombic system and typically forms fibrous, acicular prismatic crystals or masses. Radiating sprays of needlelike crystals are not uncommon. It is vitreous in luster and clear to white in color. It has a Mohs hardness of 5 to 5.5 and a low specific gravity of 2.2 to 2.4. The refractive indices are nα=1.505 nβ=1.505 nγ=1.506.