Hemihedrite Mineral Data

Hemihedrite Mineral Data +

General Hemihedrite Information

Chemical Formula:

Pb10Zn(CrO4)6(SiO4)2F2

Composition:

Molecular Weight = 3,055.52 gm

Zinc 2.14 % Zn 2.66 % ZnO

Chromium 10.21 % Cr 19.64 % CrO₃

Silicon 1.84 % Si 3.93 % SiO₂

Lead 67.81 % Pb 73.05 % PbO

Oxygen 16.76 % O

Fluorine 1.24 % F 1.24 % F

- % F -0.52 % -O=F₂

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Pb₁₀Zn(CrO₄)₆(SiO₄)₂F₂

Environment:

Secondary lead mineral from oxidized primary minerals.

IMA Status:

Approved IMA 1967

Locality:

Florence mine, Pinal County and Pack Rat claim, Whickenburg, Maricopa County, Arizona, USA. Link to MinDat.org Location Data.

Name Origin:

Named for its hemihedral crystal morphology.

Synonym:

ICSD 15175

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Hemihedrite Image

Images:

Hemihedrite

Comments: Reddish brown crystals of hemihedrite on matrix.
Location: Florence Pb-Ag mine, Whckenburg, Maricopa County, Arizona, USA. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Images:

Hemihedrite Phoenicochroite

Comments: Yellow hemihedrite crystals to 1 mm within pockets of dark red phoenicochroite crystalline aggregates on matrix.
Location: Pack Rat claim, Maricopa Co., Arizona, USA. Scale: Picture size 1.5 cm.
© Tom Loomis / Dakota Matrix

Hemihedrite Crystallography

Axial Ratios:

a:b:c =0.8299:1:0.9473

Cell Dimensions:

a = 9.497, b = 11.443, c = 10.841, Z = 1; alpha = 120.5°, beta = 92.1°, gamma = 55.84° V = 839.42 Den(Calc)= 6.04

Crystal System:

Triclinic - PinacoidalH-M Symbol ( 1) Space Group: P1

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

By Intensity(I/I_o): 3.302(1), 3.11(0.69), 3.163(0.69),

Crystal Structure:

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McLean W J , Anthony J W , American Mineralogist , 55 (1970) p.1103-1114, The crystal structure of hemihedrite

Physical Properties of Hemihedrite

Color:

Orange, Brown, Black.

Density:

6.42

Hardness:

3 - Calcite

Luster:

Vitreous (Glassy)

Streak:

saffron

Optical Properties of Hemihedrite

Gladstone-Dale:

CI meas= -0.203 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= -0.278 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2249,KPDmeas= 0.2116,KC= 0.1759

Optical Data:

Biaxial (+), a=2.105, b=2.32, g=2.65, bire=0.5450, 2V(Calc)=88, 2V(Meas)=88. Dispersion strong.

Calculated Properties of Hemihedrite

Electron Density:

r_electron=5.45 gm/cc
note: r_Hemihedrite=6.42 gm/cc.

Fermion Index

Fermion Index = 0.16138
Boson Index = 0.83862

Photoelectric:

PE_Hemihedrite=1,231.05 barns/electron
U=PE_Hemihedrite x r_electron=6,704.44 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Hemihedrite is Not Radioactive

Hemihedrite Classification

Dana Class:

36.1.1.2 (36)Compound Chromates

(36.1)with miscellaneous formulae

(36.1.1)Dana Group

36.1.1.1 Iranite Pb10Cu(CrO4)6(SiO4)2(F,OH)2 P1 1

36.1.1.2 Hemihedrite Pb10Zn(CrO4)6(SiO4)2F2 P1 1

Strunz Class:

VIII/B.28-20 VIII - Silicates

VIII/B - Nesosubsilicates, with anions unfamiliar to tetraheders, with groups [SO4]2-, [CrO4]2- and [PO4]3-

VIII/B.28 - Iranite - Macquartite series

VIII/B.28-10 Iranite Pb10Cu(CrO4)6(SiO4)2(F,OH)2 P1 1

VIII/B.28-20 Hemihedrite Pb10Zn(CrO4)6(SiO4)2F2 P1 1

VIII/B.28-25 Wherryite Pb7Cu2(SO4)4(SiO4)2(OH)2 C 2/m 2/m

VIII/B.28-30 Macquartite Pb3Cu(CrO4)(SiO3)(OH)4·2(H2O) C 2/m ? 2/m

Other Hemihedrite Information

References:

PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

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Hemihedrite

Pb10Zn(CrO4)6(SiO4)2F2
Dana No: 36.1.1.2 Strunz No: VIII/B.28-20
Locality:

Notes: