Carnallite Mineral Data

Carnallite Mineral Data

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General Carnallite Information

Chemical Formula:

KMgCl3·6(H2O)

Composition:

Molecular Weight = 277.85 gm

Potassium 14.07 % K 16.95 % K₂O

Magnesium 8.75 % Mg 14.51 % MgO

Hydrogen 4.35 % H 38.90 % H₂O

Chlorine 38.28 % Cl 38.28 % Cl

- % Cl -8.64 % -O=Cl₂

Oxygen 34.55 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

KMgCl₃·6(H₂O)

Environment:

Marine evaporites.

IMA Status:

Valid Species (Pre-IMA) 1856

Locality:

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

Name Origin:

Named after the German mining engineer, R. von Carnall (1804-1874).

Synonym:

ICSD 64691

PDF 24-869

Carnallite Image

Images:

Carnallite Rinneite

Comments: Orange to light brown rinneite with colorless carnallite.
Location: Merkers, Bad Salzungen, Rh?n, Thuringia, Germany. Scale: Picture size 4 mm.
© Thomas Witzke / Abraxas-Verlag

Images:

Carnallite

Comments: Clear crystalline massive carnallite.
Location: Stassfurt, Sachsen-Anhalt, Germany. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Images:

Carnallite Rokuhnite

Comments: Reddish brown rokuhnite, with carnallite (deliquescent).
Location: Salzdetfurth Mine, Hildesheim, near Hanover, Niedersachsen, Germany. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Carnallite Crystallography

Axial Ratios:

a:b:c =0.5956:1:1.4056

Cell Dimensions:

a = 9.56, b = 16.05, c = 22.56, Z = 12; V = 3,461.56 Den(Calc)= 1.60

Crystal System:

Orthorhombic - DipyramidalH-M Symbol (2/m 2/m 2/m) Space Group: Pcna

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

By Intensity(I/I_o): 3.3(1), 2.92(0.7), 4.65(0.5),

Forms:

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Crystal Structure:

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Schlemper E O , Sen Gupta P K , Zoltai T , American Mineralogist , 70 (1985) p.1309-1313, Refinement of the structure of carnallite, Mg(H2O)6KCl3

View Additional jPOWD Structure files for Carnallite
[1]

Physical Properties of Carnallite

Cleavage:

None

Color:

Blue, Colorless, Yellow, White, Red.

Density:

1.6

Diaphaniety:

Transparent to translucent

Fracture:

Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).

Habit:

Fibrous - Crystals made up of fibers.

Habit:

Massive - Granular - Common texture observed in granite and other igneous rock.

Habit:

Pseudo Hexagonal - Crystals show a hexagonal outline.

Hardness:

2.5 - Finger Nail

Luminescence:

Fluorescent.

Luster:

Greasy (Oily)

Streak:

white

Optical Properties of Carnallite

Gladstone-Dale:

CI meas= 0.051 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= 0.051 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2993,KPDmeas= 0.2993,KC= 0.3155

Optical Data:

Biaxial (+), a=1.467, b=1.4755, g=1.494, bire=0.0270, 2V(Calc)=70, 2V(Meas)=70. Dispersion none.

Calculated Properties of Carnallite

Electron Density:

r_electron=1.64 gm/cc
note: r_Carnallite=1.60 gm/cc.

Fermion Index

Fermion Index = 0.00893
Boson Index = 0.99107

Photoelectric:

PE_Carnallite= 4.07 barns/electron
U=PE_Carnallite x r_electron= 6.66 barns/cc.

Radioactivity:

GRapi = 207.54 (Gamma Ray American Petroleum Institute Units)

Estimated Radioactivity from Carnallite - barely detectable

Carnallite Classification

Dana Class:

11.1.2.1 (11)Halide Complexes; Alumino-fluorides

(11.1)where (A)m B (X)3

(11.1.2)Dana Group

11.1.2.1 Carnallite KMgCl3·6(H2O) Pcna 2/m 2/m 2/m

Strunz Class:

III/C.08-10 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 Carnallite Information

References:

NAME( Duda&Rejl90) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Mason68)

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Print or Cut-and-Paste your Carnallite Specimen Label here :

Carnallite

KMgCl3·6(H2O)
Dana No: 11.1.2.1 Strunz No: III/C.08-10
Locality:

Notes: