Cechite Mineral Data

Cechite Mineral Data

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General Cechite Information

Chemical Formula:

Pb(Fe++,Mn)(VO4)(OH)

Composition:

Molecular Weight = 394.54 gm

Manganese 6.96 % Mn 8.99 % MnO

Vanadium 12.91 % V 23.05 % V₂O₅

Iron 7.08 % Fe 9.11 % FeO

Hydrogen 0.26 % H 2.28 % H₂O

Lead 52.52 % Pb 56.57 % PbO

Oxygen 20.28 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

PbFe²⁺_0.5Mn²⁺_0.5(VO₄)(OH)

Environment:

On specimens form old mine dumps from a polymetallic ore deposit.

IMA Status:

Approved IMA 1981

Locality:

Vrancice, Pribram, Stredocsky Kraj, Cechy, Bohemia, Czech Republic. Link to MinDat.org Location Data.

Name Origin:

Named for Frantisek Cech (1944-), mineralogist, Charles University, Prague, Czech Republic.

Synonym:

ICSD 43079

PDF 35-530

Cechite Image

Images:

Cechite

Comments: Black tabular crystal of cechite on matrix.
Location: Alexander Gallery, Vrancice, Pr?bram, Stredocesk? Kraj, Bohemia, Czech Republic. Scale: Picture size 1.3 mm.
© Thomas Witzke / Abraxas-Verlag

Cechite Crystallography

Axial Ratios:

a:b:c =0.8057:1:0.6456

Cell Dimensions:

a = 7.607, b = 9.441, c = 6.096, Z = 4; V = 437.80 Den(Calc)= 5.99

Crystal System:

Orthorhombic - DipyramidalH-M Symbol (2/m 2/m 2/m) Space Group: Pnam

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

By Intensity(I/I_o): 3.228(1), 2.625(0.81), 5.119(0.77),

Crystal Structure:

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Pertlik F , Neues Jahrbuch fur Mineralogie, Monatshefte , 1989 (1989) p.34-40, The crystal structure of cechite, Pb(Fe,Mn)(VO4)(OH) with Fe>Mn. A mineral of the descloizite group, Locality: Vrancice, Bohemian pluton, Pribram, Czechoslovakia (Czech Republic)

Physical Properties of Cechite

Cleavage:

None

Color:

Black.

Density:

5.88

Diaphaniety:

Opaque

Fracture:

Brittle - Uneven - Very brittle fracture producing uneven fragments.

Habit:

Massive - Granular - Common texture observed in granite and other igneous rock.

Hardness:

4.5-5 - Near Apatite

Luster:

Sub Metallic

Magnetism:

Magnetic

Streak:

black

Optical Properties of Cechite

Optical Data:

Biaxial (?)

NCalc= 2.18 - from Gladstone-Dale relationship (KC = 0.1962) where Ncalc=Dcalc*KC+1
NCalc= 2.15 - from Gladstone-Dale relationship (KC = 0.1962) where Ncalc=Dmeas*KC+1

RL Anisotrophism:

Perceptible to strong, light gray to dark gray with brownish tint.

RL Bireflectance:

Weak to imperceptible.

RL Color:

Gray white with a yellowish tint, whitish, yellowish or rosy internal reflections.

Reflectivity

**Standardized Intensity (100%) Reflection Spectra of Cechite in Air**
λ	R₁	R₂	∑ R₁(λ)	∑ R₂(λ)
420 nm	17.00	19.30
440 nm	16.30	18.90
460 nm	16.00	18.50
480 nm	15.60	18.30
500 nm	15.40	18.10
520 nm	15.10	17.80
540 nm	14.80	17.60
560 nm	14.60	17.60
580 nm	14.40	17.70
600 nm	14.40	18.00
620 nm	14.50	18.30
640 nm	14.80	18.60
660 nm	15.10	18.90
680 nm	15.20	18.80
700 nm	15.30	18.70

**Calculated Relative Intensity Colors of Cechite in Air**
Relative Intensity	0%	60%	100%	120%	180%	240%	300%	360%	420%	480%	540%	590%
R₁
R₂

Calculated Properties of Cechite

Electron Density:

r_electron=5.21 gm/cc
note: r_Cechite=5.99 gm/cc.

Fermion Index

Fermion Index = 0.11798
Boson Index = 0.88202

Photoelectric:

PE_Cechite= 934.40 barns/electron
U=PE_Cechite x r_electron=4,865.89 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Cechite is Not Radioactive

Cechite Classification

Dana Class:

41.5.2.4 (41)Anhydrous Phosphates, etc. Containing Hydroxyl or Halogen

(41.5)where (A B)2 (XO4) Zq

(41.5.2)Dana Group

41.5.2.1 Descloizite PbZn(VO4)(OH) Pnam 2/m 2/m 2/m

41.5.2.2 Mottramite PbCu(VO4)(OH) Pnam 2/m 2/m 2/m

41.5.2.3 Pyrobelonite PbMn(VO4)(OH) Pnam 2/m 2/m 2/m

41.5.2.4 Cechite Pb(Fe,Mn)(VO4)(OH) Pnam 2/m 2/m 2/m

41.5.2.5 Duftite-alpha PbCu(AsO4)(OH) P 2₁2₁2₁ 2 2 2

Strunz Class:

VII/B.27-40 VII - Phosphates, Arsenates and Vanadates

VII/B - Waterfree phosphates with unfamiliar anions F, Cl, O, OH. cations of medium and big size: Mg, Cu, Zn, and Ca, Na, K, Ba, Pb

VII/B.27 - Descloizite group

VII/B.27-10 Arsendescloizite PbZn(AsO4)(OH) P 2₁2₁2₁ 2 2 2

VII/B.27-20 Descloizite PbZn(VO4)(OH) Pnam 2/m 2/m 2/m

VII/B.27-30 Mottramite PbCu(VO4)(OH) Pnam 2/m 2/m 2/m

VII/B.27-40 Cechite Pb(Fe,Mn)(VO4)(OH) Pnam 2/m 2/m 2/m

VII/B.27-50 Pyrobelonite PbMn(VO4)(OH) Pnam 2/m 2/m 2/m

Other Cechite Information

References:

NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(AntBidBlaNic4)

See Also:

Links to other databases for Cechite :
1 -Am. Min. Crystal Structure Database 2 -Athena 3 - EUROmin Project 4 -Google Images 5 -Google Scholar 6 -Handbook of Mineralogy (UofA) 7 -MinDAT 8 -MinMax(Deutsch) 9 -MinMax(English) 10 -Mineralienatlas (Deutsch) 11 -QUT Mineral Atlas 12 - WWW-MINCRYST 13 -École des Mines de Paris

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

Cechite

Pb(Fe++,Mn)(VO4)(OH)
Dana No: 41.5.2.4 Strunz No: VII/B.27-40
Locality:

Notes: