anhydrite

from The Collaborative International Dictionary of English v.0.48
Anhydrite \An*hy"drite\, n. [See {Anhydrous}.] (Min.)
   A mineral of a white or a slightly bluish color, usually
   massive. It is anhydrous sulphate of lime, and differs from
   gypsum in not containing water (whence the name).
   [1913 Webster]
    

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