Krohnkite Mineral Data

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General Krohnkite Information

Chemical Formula:

Na2Cu(SO4)2•2(H2O)

Composition:

Molecular Weight = 337.68 gm

Sodium 13.62 % Na 18.35 % Na₂O

Copper 18.82 % Cu 21.19 % Cu₂O

Hydrogen 1.19 % H 10.67 % H₂O

Sulfur 18.99 % S 47.42 % SO₃

Oxygen 47.38 % O

______ ______

100.00 % 97.63 % = TOTAL OXIDE

Empirical Formula:

Na₂Cu(SO₄)₂•2(H₂O)

Environment:

Secondary mineral in copper-bearing sulfide deposits.

IMA Status:

Valid Species (Pre-IMA) 1876

Locality:

Chuquicamata, Calama, Antofagásta Province, Chile. Link to MinDat.org Location Data.

Name Origin:

Named after B. Kroehnke, who was the first person to analyze it.

Synonym:

Kroehnkite

Krohnkite Image

Images:

Krohnkite Natrochalcite

Comments: Royal blue kröhnkite and green natrochalcite.
Location: Chiquicamata, Chile. Scale: 3.5 x 2 cm.
© John Veevaert

Krohnkite Crystallography

Axial Ratios:

a:b:c =0.4584:1:0.4356

Cell Dimensions:

a = 5.8, b = 12.651, c = 5.512, Z = 2; beta = 108.45° V = 383.66 Den(Calc)= 2.92

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: P 2₁/c

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

By Intensity(I/I_o): 6.32(1), 3.28(0.75), 2.928(0.65),

Forms:

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Forms: ( 1 1 1) ( 0 1 0) ( 0 1 1) ( 1 3 0) ( 1 3 1) ( 1 2 0) ( 0 1 2) ( 1 0 0) ( 1 1 0)

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Crystal Structure:

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Hawthorne F C , Ferguson R B , Acta Crystallographica, Section B , 31 (1975) p.1753-1755, Refinement of the crystal structure of krohnkite, Locality: Chuquicamata, Chile

Physical Properties of Krohnkite

Cleavage:

{010} Perfect, {011} Good

Color:

Blue, Dark sky blue, Greenish blue, Yellowish green.

Density:

2.06 - 2.9, Average = 2.48

Diaphaneity:

Transparent to Translucent

Fracture:

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

Habit:

Encrustations - Forms crust-like aggregates on matrix.

Habit:

Fibrous - Crystals made up of fibers.

Habit:

Massive - Fibrous - Distinctly fibrous fine-grained forms.

Hardness:

2.5-3 - Finger Nail-Calcite

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Krohnkite

Gladstone-Dale:

CI meas= -0.132 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= 0.039 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1967,KPDmeas= 0.2316,KC= 0.2047
Ncalc = 1.42 - 1.6

Optical Data:

Biaxial (-), a=1.544, b=1.578, g=1.601, bire=0.0570, 2V(Calc)=76, 2V(Meas)=78.7.

Calculated Properties of Krohnkite

Electron Density:

Bulk Density (Electron Density)=2.89 gm/cc
note: Specific Gravity of Krohnkite =2.92 gm/cc.

Fermion Index:

Fermion Index = 0.0016535964
Boson Index = 0.9983464036

Photoelectric:

PE_Krohnkite= 9.42 barns/electron
U=PE_Krohnkite x rElectron Density= 27.20 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Krohnkite is Not Radioactive

Krohnkite Classification

Dana Class:

29.03.02.01 (29)Hydrated Acid and Sulfates

(29.03)where (A+)2 B (XO4)2 · x(H2O)

(29.03.02)Dana Group

29.03.02.01 Krohnkite Na2Cu(SO4)2•2(H2O) P 2₁/c 2/m

Strunz Class:

07.CC.30 07 - SULFATES (SELENATES, TELLURATES)

07.C - Sulfates (selenates, etc.) without Additional Anions, with H2O

07.CC -With medium-sized and large cations

07.CC.30 Krohnkite Na2Cu(SO4)2•2(H2O) P 2₁/c 2/m

Other Krohnkite Information

References:

NAME( Duda&Rejl90) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Ford32)

See Also:

Links to other databases for Krohnkite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - GeoScienceWorld
5 - Google Images
6 - Google Scholar
7 - Handbook of Mineralogy (MinSocAm)
8 - Handbook of Mineralogy (UofA)
9 - MinDAT
10 - Mineralienatlas (Deutsch)
11 - Online Mineral Museum
12 - QUT Mineral Atlas
13 - Ruff.Info
14 - WWW-MINCRYST

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

Krohnkite

Na2Cu(SO4)2•2(H2O)
Dana No: 29.03.02.01 Strunz No: 07.CC.30
Locality:

Notes: