Beidellite

General Information: Chemical Formula:Na0.5Al2(Si3.5Al0.5)O10(OH)2·n(H2O) Composition:(Molecular Weight = 389.27 gm)Sodium 2.95 % NaAluminum 17.33 % AlSilicon 25.25 % SiHydrogen 1.04 % H Oxygen 53.43 % O  Empirical Formula: Na0.5Al2.5Si3.5O10(OH)2·(H2O) Locality:Beidell, Colorado, USA.. Name Origin:Named after its locality.Physical Properties: Cleavage:[001] Perfect Color:white, gray, reddish white, brownish white, or pale yellow. Density:2 - 2.3, Average = 2.15 Diaphaniety:Translucent to subtranslucent Habits:Earthy - Dull, clay-like texture with no visible crystalline affinities, (e.g. howlite)., , Hardness:1-2 - Between Talc and Gypsum Luminescence:Non-fluorescent. Luster:Earthy (Dull) Streak:whiteMore details...

(Na2,Ca)0.15Al2(Si,Al)4O10(OH)2 n(H2O)