- Tachyhydrite
Tachyhydrite is an unstable mineral, a hydrous
chloride ofcalcium andmagnesium with formula: CaMg2Cl6·12H2O. It is a rare component of marineevaporite salt deposits. Upon exposure to moist air it rapidly deliquesces and dissolves.It forms a colorless to yellow
trigonal crystals with a vitreous luster. It is soft with aMohs hardness of 2 and has a lowspecific gravity of 1.66. It has good cleavage in three directions and typically occurs in crystalline masses.It was first described in 1856 for an occurrence in Stassfurt,
Saxony ,Germany . Its name is from the Greek for "quick water", in reference to its ready deliquescence.According to a patent filed years ago by a Halliburton researcher, high strength hydrochloric acid treatment of magnesium containing carbonates creates tachyhydrite, which will seal the rock pores and inhibit oil flow unless washed with a light acid or water before and after the treatment. [ [http://www.google.com/patents?vid=USPAT3550686&id=nvxkAAAAEBAJ&printsec=description&zoom=4&dq=%22Duncan%22+%22UTILIZATION+OF+HIGH+STRENGTH+ACID+ON+DOLOMITE%22+#PPP4,M1 403 Forbidden ] ]
References
* [http://webmineral.com/data/Tachyhydrite.shtml Webmineral data]
* [http://www.mindat.org/min-3865.html Mindat with location data]
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