Posnjakite Mineral Data

Posnjakite Mineral Data +

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General Posnjakite Information

Chemical Formula:

Cu4(SO4)(OH)6·(H2O)

Composition:

Molecular Weight = 470.31 gm

Copper 54.05 % Cu 67.65 % CuO

Hydrogen 1.71 % H 15.32 % H₂O

Sulfur 6.82 % S 17.02 % SO₃

Oxygen 37.42 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Cu₄(SO₄)(OH)₆·(H₂O)

IMA Status:

Approved IMA 1967

Locality:

Link to MinDat.org Location Data.

Name Origin:

Named after the geochemist, E. W. Posnjak (1888-1949).

Synonym:

ICSD 100276

PDF 43-670

Posnjakite Image

Images:

Posnjakite

Comments: Waxy blue aggregates of posnjakite.
Location: Ecton mine, Audubon, Montgomery County, Pennsylvania, USA. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Posnjakite Crystallography

Axial Ratios:

a:b:c =2.2454:1:1.6673

Cell Dimensions:

a = 14.236, b = 6.34, c = 10.571, Z = 4; beta = 102.917° V = 929.96 Den(Calc)= 3.36

Crystal System:

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

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

By Intensity(I/I_o): 6.94(1), 3.47(0.3), 2.7(0.25),

Crystal Structure:

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Mellini M , Merlino S , Zeitschrift fur Kristallographie , 149 (1979) p.249-257, Posnjakite: [Cu4(OH)6(H2O)O] octahedral sheets in its structure, Locality: Fowey Consols, England

Physical Properties of Posnjakite

Cleavage:

[???] Perfect

Color:

Blue, Dark blue.

Density:

3.4

Fracture:

Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern.

Habit:

Crystalline - Fine - Occurs as well-formed fine sized crystals.

Habit:

Encrustations - Forms crust-like aggregates on matrix.

Habit:

Platy - Sheet forms (e.g. micas).

Hardness:

2.5-3 - Finger Nail-Calcite

Luster:

Vitreous (Glassy)

Streak:

greenish blue

Optical Properties of Posnjakite

Gladstone-Dale:

CI meas= 0 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.011 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1995,KPDmeas= 0.1972,KC= 0.1972

Optical Data:

Biaxial (-), a=1.625, b=1.68, g=1.706, bire=0.0810, 2V(Calc)=66, 2V(Meas)=57.

Calculated Properties of Posnjakite

Electron Density:

r_electron=3.30 gm/cc
note: r_Posnjakite=3.40 gm/cc.

Fermion Index

Fermion Index = 0.00069
Boson Index = 0.99931

Photoelectric:

PE_Posnjakite= 23.94 barns/electron
U=PE_Posnjakite x r_electron= 78.94 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Posnjakite is Not Radioactive

Posnjakite Classification

Dana Class:

31.4.1.1 (31)Hydrated Sulfates Containing Hydroxyl or Halogen

(31.4)where (A+ B++)4 (XO4) Zq·x(H2O)

(31.4.1)Dana Group

31.4.1.1 Posnjakite Cu4(SO4)(OH)6·(H2O) C 2/c 2/m

Strunz Class:

VI/D.03-10 VI - Sulfates,Chromates,Molybdates and Tungstates

VI/D - Water-bearing sulfates with unfamiliar anions. cations of medium size

VI/D.03 - Langite series, Posnjakite - Nakuriite

VI/D.03-10 Posnjakite Cu4(SO4)(OH)6·(H2O) C 2/c 2/m

VI/D.03-20 Langite Cu4(SO4)(OH)6·2(H2O) Pc m

VI/D.03-30 Wroewolfeite Cu4(SO4)(OH)6·2(H2O) Pc m

VI/D.03-40 Namuwite (Zn,Cu)4(SO4)(OH)6·4(H2O) Unk Hex

VI/D.03-50 Guarinoite (Zn,Co,Ni)6(SO4)(OH,Cl)10·5(H2O) P 6₃/m,P 6₃, or P 6₃22 Hex

VI/D.03-55 Theresemagnanite (Co,Zn,Ni)6(SO4)(OH,Cl)10·8(H2O) P 6₃ 6

VI/D.03-60 Schulenbergite (Cu,Zn)7(SO4,CO3)2(OH)10·3(H2O) P 3 or P 3- Trig

VI/D.03-65 Christelite! Zn3Cu2(SO4)2(OH)6·4(H2O) P1 1

VI/D.03-70 Ktenasite (Cu,Zn)5(SO4)2(OH)6·6(H2O) P 2₁/c 2/m

VI/D.03-75 Ramsbeckite (Cu,Zn)15(SO4)4(OH)22·6(H2O) P 2₁/a 2/m

VI/D.03-80 Campigliaite Cu4Mn(SO4)2(OH)6·4(H2O) C 2 2

VI/D.03-90 Nakauriite (Mn,Ni,Cu)8(SO4)4(CO3)(OH)6·48(H2O) Unk Ortho

Other Posnjakite Information

References:

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

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

Posnjakite

Cu4(SO4)(OH)6·(H2O)
Dana No: 31.4.1.1 Strunz No: VI/D.03-10
Locality:

Notes: