gyrolite

{{Infobox mineral | name = Gyrolite | image = Gyrolite - Malad quarry, Mumbai, Maharashtra, India.jpg | imagesize = 275px | alt = | caption = Spherical colorless gyrolite crystals from Malad quarry, India | category = Phyllosilicate minerals | formula = NaCa16(Si23Al)O60(OH)8·14H2O | IMAsymbol = Gyr | strunz = 9.EE.30 | dana = 73.2.2c.1 | system = Triclinic | class = Pinacoidal () (same H-M symbol) | symmetry = P | unit cell = a = 9.74, b = 9.74 c = 22.4 [Å]; α = 95.71° β = 91.51°, γ = 120.01°; Z = 4 | color = White, colorless, green, yellow or brown | habit = Globular, compact, lamellar, platy | twinning = Lamellar | cleavage = Perfect on {001} | fracture = | tenacity = Brittle | mohs = | luster = Vitreous, pearly | streak = | diaphaneity = Transparent, translucent, opaque | gravity = | density = 2.45–2.51 | polish = | opticalprop = Biaxial (−) | refractive = nα = 1.535 nβ = 1.548 nγ = 1.549 | birefringence = δ = 0.0140 | pleochroism = | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | prop1 = | prop1text = | references = }}

Gyrolite, NaCa16(Si23Al)O60(OH)8·14H2O, is a rare silicate mineral (basic sodium calcium silicate hydrate: N-C-S-H, in cement chemist notation) belonging to the class of phyllosilicates. Gyrolite is also often associated with zeolites. It is most commonly found as spherical or radial formations in hydrothermally altered basalt and basaltic tuffs. These formations can be glassy, dull or fibrous in appearance.