- Tachhydrite Tach*hy"drite, n. [Gr. tachy`s quick + "y`dwr water. So named from its ready deliquescence.] (Min.) A hydrous chloride of calcium and magnesium occurring in yellowish masses which rapidly deliquesce upon exposure. It is found in the salt mines at Stassfurt. [1913 Webster]
The Collaborative International Dictionary of English. 2000.