Tachyhydrite Mineral Data

Tachyhydrite Mineral Data +

General Tachyhydrite Information

Chemical Formula:

CaMg2Cl6·12(H2O)

Composition:

Molecular Weight = 517.59 gm

Calcium 7.74 % Ca 10.83 % CaO

Magnesium 9.39 % Mg 15.57 % MgO

Hydrogen 4.67 % H 41.77 % H₂O

Chlorine 41.10 % Cl 41.10 % Cl

- % Cl -9.27 % -O=Cl₂

Oxygen 37.09 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

CaMg₂Cl₆·12(H₂O)

Environment:

Rare constituent of marine salt deposits.

IMA Status:

Valid Species (Pre-IMA) 1856

Locality:

Stassfurt, Province of Saxony, Germany. Link to MinDat.org Location Data.

Name Origin:

From the Greek for "quick water", in allusion to its ready deliquescence.

Synonym:

ICSD 16434

PDF 34-788

Tachyhydrite Image

Images:

Tachyhydrite

Comments: Translucent pink tinted granular tachyhydrite.
Location: Stassfurt, Sachsen-Anhalt, Germany. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Tachyhydrite Crystallography

Axial Ratios:

a:c = 1:1.70856

Cell Dimensions:

a = 10.136, c = 17.318, Z = 3; V = 1,540.85 Den(Calc)= 1.67

Crystal System:

Trigonal - RhombohedralH-M Symbol ( 3) Space Group: P 3

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 2.6(1), 3.09(0.5), 3.8(0.3),

Crystal Structure:

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Clark J R , Evans H T , Erd R C , Acta Crystallographica, Section B , 36 (1980) p.2736-2739, Tachyhydrite, dimagnesium calcium chloride 12-hydrate, Locality: synthetic

Physical Properties of Tachyhydrite

Cleavage:

[1011] Good, [1011] Good, [1011] Good

Color:

Colorless, Yellow.

Density:

1.66

Diaphaniety:

Transparent to translucent

Habit:

Deliquescent - Crystals absorb water from the air and melt or otherwise deteriorate.

Habit:

Massive - Uniformly indistinguishable crystals forming large masses.

Habit:

Tastes Bitter - Bitter taste from water soluble Mg or Ca compounds.

Hardness:

2 - Gypsum

Luster:

Vitreous - Greasy

Streak:

white

Optical Properties of Tachyhydrite

Gladstone-Dale:

CI meas= 0.046 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= 0.052 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.309,KPDmeas= 0.3108,KC= 0.3258

Optical Data:

Uniaxial (-), e=1.512, w=1.52, bire=0.0080.

Calculated Properties of Tachyhydrite

Electron Density:

r_electron=1.71 gm/cc
note: r_Tachyhydrite=1.66 gm/cc.

Fermion Index

Fermion Index = 0.00968
Boson Index = 0.99032

Photoelectric:

PE_Tachyhydrite= 3.82 barns/electron
U=PE_Tachyhydrite x r_electron= 6.52 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Tachyhydrite is Not Radioactive

Tachyhydrite Classification

Dana Class:

11.5.5.1 (11)Halide Complexes; Alumino-fluorides

(11.5)where (A)m B (X)6

(11.5.5)Dana Group

11.5.5.1 Tachyhydrite CaMg2Cl6·12(H2O) P 3 3

Strunz Class:

III/C.08-30 III - Halogenides

III/C - Double halogenides with water, Chlorides

III/C.08 - Carnallite - Tachyhydrite series

III/C.08-10 Carnallite KMgCl3·6(H2O) Pcna 2/m 2/m 2/m

III/C.08-20 Koenenite Na4Mg4Cl12·Mg5Al4(OH)22 R 3m 3 2/m

III/C.08-30 Tachyhydrite CaMg2Cl6·12(H2O) P 3 3

Other Tachyhydrite Information

References:

NAME( Ford32) PHYS. PROP.(Ford32) OPTIC PROP.(Ford32)

See Also:

Links to other databases for Tachyhydrite :
1 -Am. Min. Crystal Structure Database 2 -Athena 3 - EUROmin Project 4 -Google Images 5 -Google Scholar 6 -Handbook of Mineralogy (UofA) 7 -MinDAT 8 -MinMax(Deutsch) 9 -MinMax(English) 10 -Mineralienatlas (Deutsch) 11 -QUT Mineral Atlas 12 - WWW-MINCRYST 13 -École des Mines de Paris

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Tachyhydrite

CaMg2Cl6·12(H2O)
Dana No: 11.5.5.1 Strunz No: III/C.08-30
Locality:

Notes: