Log InRegister
Home PageAbout MindatThe Mindat ManualHistory of MindatCopyright StatusWho We AreContact UsAdvertise on Mindat
Donate to MindatCorporate SponsorshipSponsor a PageSponsored PagesMindat AdvertisersAdvertise on Mindat
Learning CenterWhat is a mineral?The most common minerals on earthInformation for EducatorsMindat Articles
Minerals by PropertiesMinerals by ChemistryAdvanced Locality SearchRandom MineralRandom LocalitySearch by minIDLocalities Near MeSearch ArticlesSearch GlossaryMore Search Options
Search For:
Mineral Name:
Locality Name:
The Mindat ManualAdd a New PhotoRate PhotosLocality Edit ReportCoordinate Completion ReportAdd Glossary Item
Mining CompaniesStatisticsThe ElementsUsersBooks & MagazinesMineral MuseumsMineral Shows & EventsThe Mindat DirectoryDevice Settings
Photo SearchPhoto GalleriesNew Photos TodayNew Photos YesterdayMembers' Photo GalleriesPast Photo of the Day Gallery


This page is currently not sponsored. Click here to sponsor this page.
Hide all sections | Show all sections

About TachyhydriteHide

CaMg2Cl6 · 12H2O
Colourless, light yellow
Specific Gravity:
Crystal System:
From Greek ταχίς quick, and ϋδωρ, water, alluding to its ready deliquescence.
A very hygroscopic hydrated chloride mineral.

Classification of TachyhydriteHide

Approved, 'Grandfathered' (first described prior to 1959)

B : Simple halides, with H2O
B : M:X = 1:2

5 : AmBX6

8 : Halides - Fluorides, Chlorides, Bromides and Iodides; also Fluoborates and Fluosilicates
4 : Halides of the alkaline earths and Mg

Physical Properties of TachyhydriteHide

Colourless, light yellow
On {10_11}.
1.667 g/cm3 (Measured)    

Optical Data of TachyhydriteHide

Uniaxial (-)
RI values:
nω = 1.520 nε = 1.512
Max Birefringence:
δ = 0.008
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Not dichroic.

Chemical Properties of TachyhydriteHide

CaMg2Cl6 · 12H2O

Crystallography of TachyhydriteHide

Crystal System:
Massive; in rounded masses. Crystals rhombohedral with {0001} (artificial crystals).
Exhibits twin lamellae at times; probably secondary and due to pressure.

Type Occurrence of TachyhydriteHide

Geological Setting of Type Material:
Oceanic-type, potash-rich saline deposit.
Associated Minerals at Type Locality:

Other Language Names for TachyhydriteHide

Common AssociatesHide

BischofiteMgCl2 · 6H2O
CarnalliteKMgCl3 · 6H2O
KainiteKMg(SO4)Cl · 3H2O
KieseriteMgSO4 · H2O
Associated Minerals Based on Photo Data:
Carnallite2 photos of Tachyhydrite associated with Carnallite on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

3.BB.05EriochalciteCuCl2 · 2H2OOrth. mmm (2/m 2/m 2/m)
3.BB.10RokühniteFeCl2 · 2H2OMon.
3.BB.15BischofiteMgCl2 · 6H2OMon. 2/m : B2/m
3.BB.20NickelbischofiteNiCl2 · 6H2OMon.
3.BB.25SinjariteCaCl2 · 2H2OTet.
3.BB.30AntarcticiteCaCl2 · 6H2OTrig. 3 2 : P3 2 1

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

8.4.1SellaiteMgF2Tet. 4/mmm (4/m 2/m 2/m) : P42/mnm
8.4.2NeighboriteNaMgF3Orth. mmm (2/m 2/m 2/m)
8.4.3BischofiteMgCl2 · 6H2OMon. 2/m : B2/m
8.4.4KorshunovskiteMg2Cl(OH)3 · 4H2OTric.
8.4.5CarnalliteKMgCl3 · 6H2OOrth. mmm (2/m 2/m 2/m) : Pnna
8.4.7FluoriteCaF2Iso. m3m (4/m 3 2/m) : Fm3m
8.4.8SinjariteCaCl2 · 2H2OTet.
8.4.9AntarcticiteCaCl2 · 6H2OTrig. 3 2 : P3 2 1
8.4.10ChlorocalciteKCaCl3Orth. mmm (2/m 2/m 2/m) : Pnma
8.4.12JarliteNa(Sr,Na)7MgAl6F32(OH,H2O)2Mon. 2/m
8.4.14TikhonenkoviteSr[AlF4(OH)(H2O)]Mon. 2/m : P21/b
8.4.15AcuminiteSr[AlF4(OH)(H2O)]Mon. 2/m : B2/b
8.4.16FrankdicksoniteBaF2Iso. m3m (4/m 3 2/m) : Fm3m
8.4.18BøgvaditeNa2SrBa2Al4F20Mon. 2/m

Other InformationHide

Readily soluble in water.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Industrial Uses:
Source of potassium.

References for TachyhydriteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Rammelsberg (1856) Annalen der Physik, Halle, Leipzig: 98: 261.
Des Cloizeaux, A. (1867) Nouvelles recherches sur les propriétés optique des cristaux, naturels ou artificiels, et sur les variations que ces propriétés éprouvent sous l’influence de la chaleur. 222pp., Paris. (Institut imperial de France, Mémoires 18): 74.
Groth, P. (1874) Tabellarische Übersicht der Mineralien nach ihren krystallographish-chemischen Beziehungen. Braunschweig. 1st. edition: 74.
de Schulten (1890) Comptes rendus de l’Académie des sciences de Paris: 111: 928.
Boeke (1908) Zeitschrift für Kristallographie, Mineralogie und Petrographie, Leipzig: 45: 354.
Kling (1915) Centralblatt für Mineralogie, Geologie und Paleontologie, Stuttgart: 14, 44.
Jung (1926) Centralblatt für Mineralogie, Geologie und Paleontologie, Stuttgart: 274.
Doelter, C. (1928) Handbuch der Mineral-chemie (in 4 volumes divided into parts): 4[2]: 1219.
Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II: Halides, Nitrates, Borates, Carbonates, Sulfates, Phosphates, Arsenates, Tungstates, Molybdates, Etc. John Wiley and Sons, Inc., New York, 7th edition, revised and enlarged: 95-96.
Acta Crystallographica (1980): B36: 2736-2739.

Internet Links for TachyhydriteHide

Localities for TachyhydriteHide

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
  • Salzburg
    • Hallein
      • Dürrnberg
A. Strasser: Die Minerale Salzburgs, 1989
  • Sergipe
    • Rosário do Catete
  • Lower Saxony
    • Celle
      • Hänigsen
Bode "Mineralien und Fundstellen BRD" from 1989 ISBN 3-925094-24-5 Pg.9
      • Wathlingen
Weiss: "Mineralfundstellen, Deutschland West", Weise (Munich), 1990
    • Göttingen
      • Reyershausen
Niemann, H. (1960): Contributions to Mineralogy and Petrology 7, 137-165.
    • Nordhorn
      • Frenswegen
Füchtbauer, H., and Goldschmidt, H. (1956): Contributions to Mineralogy and Petrology 5(3), 187-203.
    • Peine
Dana 6: Appendix 3: 40; Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II: 91.
    • Vienenburg
Weiss: "Mineralfundstellen, Deutschland West", Weise (Munich), 1990
  • Saxony-Anhalt
    • Halle
      • Teutschenthal
Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II: 95.
    • Stassfurt Potash deposit
      • Egeln
        • Tarthun
No reference listed
Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II: 95; Wittern: "Mineralfundorte in Deutschland", 2001
  • Greater Poland
Wachowiak, J., Pieczka, A. (2016): Motukoreaite from the Kłodawa Salt Dome, Central Poland. Mineralogical Magazine, 80, 277-289
Republic of Congo (Brazzaville)
  • Kouilou Department
Henry Rauche (2009) Updated Reserve and Resource Estimate for MagMinerals Kouilou Potash Project, Republic of Congo
  • Maha Sarakham Province
Tabakh, M. E., Schreiber, B. C., Utha‐Aroon, C., Coshell, L., & Warren, J. K. (1998). Diagenetic origin of basal anhydrite in the Cretaceous Maha Sarakham salt: Khorat Plateau, NE Thailand. Sedimentology, 45(3), 579-594.
  • England
    • Co. Durham
      • Stockton-on-Tees
        • Billingham
Mineralogical Magazine 1959 32 : 172-175.
  • New Mexico
Northrop, Minerals of New Mexico, 3rd. rev. ed. (1996)
Mineral and/or Locality  
Mindat.org is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization. Public Relations by Blytheweigh.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2019, except where stated. Mindat.org relies on the contributions of thousands of members and supporters.
Privacy Policy - Terms & Conditions - Contact Us Current server date and time: March 24, 2019 13:20:53 Page generated: March 14, 2019 01:58:48
Go to top of page