Posnjakite Mineral Data

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).

Name Pronunciation:

Posnjakite + Pronunciation

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 - Prismatic H-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),

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
Ncalc = 1.66 - 1.67

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:

Bulk Density (Electron Density)=3.30 gm/cc
note: Specific Gravity of Posnjakite =3.40 gm/cc.

Fermion Index:

Fermion Index = 0.00069355
Boson Index = 0.99930645

Photoelectric:

PE_Posnjakite= 23.94 barns/electron
U=PE_Posnjakite x rElectron Density= 78.94 barns/cc.

Radioactivity:

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

Posnjakite Classification

Dana Class:

31.04.01.01 (31)Hydrated Sulfates Containing Hydroxyl or Halogen

(31.04)where (A+ B++)4 (XO4) Zqï¿½x(H2O)

(31.04.01)Dana Group

31.04.01.01 Posnjakite Cu4(SO4)(OH)6•(H2O) C 2/c 2/m

Strunz Class:

07.DD.10 07 - SULFATES (SELENATES, TELLURATES)

07.D - Sulfates (selenates, etc.) with additional anions, with H2O

07.DD -With only medium-sized cations; sheets of edge-sharing octahedra

07.DD.10 Langite Cu4(SO4)(OH)6•2(H2O) Pc m

07.DD.10 Posnjakite Cu4(SO4)(OH)6•(H2O) C 2/c 2/m

07.DD.10 Wroewolfeite Cu4(SO4)(OH)6•2(H2O) Pc m

Other Posnjakite Information

References:

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

See Also:

Links to other databases for Posnjakite :
1 - Alkali-Nuts(English)
2 - Alkali-Nuts(Francais)
3 - Am. Min. Crystal Structure Database
4 - Athena
5 - EUROmin Project
6 - Ecole des Mines de Paris
7 - GeoScienceWorld
8 - Google Images
9 - Google Scholar
10 - Handbook of Mineralogy (MinSocAm)
11 - Handbook of Mineralogy (UofA)
12 - MinDAT
13 - Mineralienatlas (Deutsch)
14 - Online Mineral Museum
15 - QUT Mineral Atlas
16 - Ruff.Info
17 - WWW-MINCRYST

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Posnjakite

Cu4(SO4)(OH)6•(H2O)
Dana No: 31.04.01.01 Strunz No: 07.DD.10
Locality:

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