Emily Dickinson Lexicon

MES'O-TYPE, n. [Gr. μεσος, middle, and τυπος, form, type.]

Prismatic zeolite; a membrane divided into three subspecies, fibrous zeolite, natrolite, and mealy zeolite. This is said by some writers to be so named from its property, when transparent, of doubling images. Others say it is a mean form between stilbite and analcime. Dict. Jameson. Phillips.