Ca(Al₂Si₇O₁₈)⋅7H₂O A white, brown, or yellow mineral belonging to the zeolite family of silicates; crystallizes in the monoclinic system, occurs in sheaflike aggregates of tabular crystals, and has pearly luster; hardness is 3.5-4 on Mohs scale, and specific gravity is 2.1-2.2. Also known as desmine.