Lukrahnite Mineral Data

General Lukrahnite Information

Chemical Formula:

Ca(Cu,Zn)(Fe,Zn)(AsO4)2(OH,H2O)2

Composition:

Molecular Weight = 468.74 gm

Calcium 8.55 % Ca 11.96 % CaO

Zinc 6.98 % Zn 8.68 % ZnO

Iron 9.53 % Fe 13.63 % Fe₂O₃

Copper 8.13 % Cu 9.16 % Cu₂O

Arsenic 31.97 % As 49.03 % As₂O₅

Hydrogen 0.71 % H 6.34 % H₂O

Oxygen 34.13 % O

______ ______

100.00 % 98.81 % = TOTAL OXIDE

Empirical Formula:

CaCu_0.6Zn_0.5Fe³⁺_0.8(AsO₄)₂(H₂O)_1.3(OH)_0.7

Environment:

Ca analog of gartrellite. Tsumcorite group

IMA Status:

Approved IMA 1999 (Dana # Added)

Locality:

Tsumeb mine, Namibia. Link to MinDat.org Location Data.

Name Origin:

Named for Ludger Krahn (1957-), Geologischer Dienst Nordrhein-Westfalen, geologist who provided the initial specimen for study.

Synonym:

IMA1999-030

Lukrahnite Crystallography

Axial Ratios:

a:b:c =0.9851:1:1.3358

Cell Dimensions:

a = 5.457, b = 5.539, c = 7.399, Z = 1; alpha = 68.43°, beta = 68.9°, gamma = 69.44° V = 181.68 Den(Calc)= 4.28

Crystal System:

Triclinic - Pinacoidal H-M Symbol ( 1) Space Group: P1

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

By Intensity(I/I_o): 3.416(1)(112), 2.927(0.64)(111), 3.186(0.4)(012,102),2.533(0.3)(201,212), 2.7(0.3)(211), 2.832(0.26), 2.468(0.25), 4.953(0.22),

Physical Properties of Lukrahnite

Cleavage:

None

Color:

Yellow.

Diaphaneity:

Transparent

Fracture:

Brittle - Generally displayed by glasses and most non-metallic minerals.

Habit:

Aggregates - Made of numerous individual crystals or clusters.

Habit:

Microscopic Crystals - Crystals visible only with microscopes.

Habit:

Spherical - Spherical, rounded aggregates.

Hardness:

5 - Apatite

Luster:

Vitreous - Adamantine

Streak:

light yellow

Optical Properties of Lukrahnite

Gladstone-Dale:

CI calc= -0.005 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2051,KC= 0.2042
Ncalc = 1.85

Optical Data:

Biaxial (+), a=1.83, b=1.834, g=1.89, bire=0.0600

Calculated Properties of Lukrahnite

Electron Density:

Bulk Density (Electron Density)=3.94 gm/cc
note: Specific Gravity of Lukrahnite =4.15 gm/cc.

Fermion Index:

Fermion Index = 0.0051607569
Boson Index = 0.9948392431

Photoelectric:

PE_Lukrahnite= 32.96 barns/electron
U=PE_Lukrahnite x rElectron Density= 129.86 barns/cc.

Radioactivity:

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

Lukrahnite Classification

Dana Class:

43.02.02.03 (43)Compound Phosphates, etc.

(43.02)(Anhydrous Normal Compound Anions)

(43.02.02)Gartrellite Group

43.02.02.01 Gartrellite Pb(Cu,Fe)2(AsO4,SO4)2(CO3,H2O)0.7 P1,P 1 Tri

43.02.02.02 Zincgartrellite! Pb(Zn,Fe,Cu)2(AsO4)2(OH,H2O)2 P1 1

43.02.02.03 Lukrahnite! Ca(Cu,Zn)(Fe,Zn)(AsO4)2(OH,H2O)2 P1 1

Strunz Class:

08.CG.20 08 - PHOSPHATES, ARSENATES, VANADATES

08.C - Phosphates without Additional Anions, with H2O

08.CG -With large and medium-sized cations, RO4:H2O = 1:1

08.CG.20 Gartrellite Pb(Cu,Fe)2(AsO4,SO4)2(CO3,H2O)0.7 P1,P 1 Tri

08.CG.20 Helmutwinklerite PbZn2(AsO4)2•2(H2O) P1 1

08.CG.20 Phosphogartrellite! PbCuFe(PO4)2(OH,H2O)2 P1 1

08.CG.20 Zincgartrellite! Pb(Zn,Fe,Cu)2(AsO4)2(OH,H2O)2 P1 1

08.CG.20 Rappoldite! Pb(Co,Ni,Zn,)2(AsO4)2•2(H2O) P1 1

08.CG.20 Lukrahnite! Ca(Cu,Zn)(Fe,Zn)(AsO4)2(OH,H2O)2 P1 1

Other Lukrahnite Information

References:

NAME( AmMin, Vol 87, p 766) PHYS. PROP.(AmMin, Vol 87, p 766) OPTIC PROP.(AmMin, Vol 87, p 766)

See Also:

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

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Lukrahnite

Ca(Cu,Zn)(Fe,Zn)(AsO4)2(OH,H2O)2
Dana No: 43.02.02.03 Strunz No: 08.CG.20
Locality:

Notes:

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