kieserite

from WordNet (r) 3.0 (2006)

kieserite
    n 1: a white mineral consisting of hydrous magnesium sulfate
         often found in salt mines

from The Collaborative International Dictionary of English v.0.48

Kieserite \Kie"ser*ite\, n. [Named after Prof. Kieser, of Jena.]
   (Min.)
   Hydrous sulphate of magnesia found at the salt mines of
   Stassfurt, Prussian Saxony.
   [1913 Webster]