Kentrolite Mineral Data

General Kentrolite Information

Chemical Formula:

Pb2Mn+++2Si2O9

Composition:

Molecular Weight = 718.61 gm

Magnesium 0.03 % Mg 0.06 % MgO

Titanium 0.27 % Ti 0.44 % TiO₂

Manganese 9.79 % Mn 14.06 % Mn₂O₃

Aluminum 0.15 % Al 0.28 % Al₂O₃

Iron 4.74 % Fe 6.78 % Fe₂O₃

Silicon 7.89 % Si 16.89 % SiO₂

Lead 57.09 % Pb 61.50 % PbO

Oxygen 20.04 % O

______ ______

100.00 % 100.01 % = TOTAL OXIDE

Empirical Formula:

Pb_1.98Mn³⁺_1.28Fe³⁺_0.61Al_0.04Ti_0.04Mg_0.01Si_2.02O₉

Environment:

In a cavity in calcite in a metamorphosed stratiform zinc deposit. Forms a series with melanotekite.

IMA Status:

Valid Species (Pre-IMA) 1880

Locality:

The unknown type locality is southern Chile. Vermland, Sweden. Link to MinDat.org Location Data.

Name Origin:

From the Greek for spike or thorn, for its prismatic habit.

Name Pronunciation:

Kentrolite + Pronunciation

Kentrolite Image

Images:

Kentrolite

Comments: Brownish red grains of kentrolite in matrix.
Location: Langban mine, Varmland, Sweden. Scale: Picture size 5 mm.
© Tom Loomis / Dakota Matrix

Kentrolite Crystallography

Axial Ratios:

a:b:c =0.6317:1:0.9043

Cell Dimensions:

a = 6.961, b = 11.018, c = 9.964, Z = 4; V = 764.20 Den(Calc)= 6.25

Crystal System:

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

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

By Intensity(I/I_o): 2.74(1), 2.86(1), 2.9(1),

Crystal Structure:

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Help on Above

Moore P B , Sen Gupta P K , Shen J , Schlemper E O , American Mineralogist , 76 (1991) p.1389-1399, The kentrolite-melanotekite series, 4Pb2(Mn,Fe)2O2[Si2O7]: Chemical, crystallographic relations, lone-pair splitting, and cation relation to 8URe2

Physical Properties of Kentrolite

Cleavage:

{110} Distinct

Color:

Dark reddish brown, Reddish black.

Density:

6.19

Diaphaneity:

Translucent to subtranslucent

Fracture:

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

Habit:

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

Habit:

Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).

Habit:

Wheat Sheaf - Bundle shaped aggregates resembling wheat sheafs after hand reaping wheat.

Hardness:

5 - Apatite

Luster:

Sub Metallic

Streak:

dark brown

Optical Properties of Kentrolite

Gladstone-Dale:

CI meas= -0.062 (Fair) - where the CI = (1-KPDmeas/KC)
CI calc= -0.052 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1925,KPDmeas= 0.1944,KC= 0.183
Ncalc = 2.13 - 2.14

Optical Data:

Biaxial (+), a=2.1, b=2.2, g=2.31, bire=0.2100, 2V(Calc)=88, 2V(Meas)=88. Dispersion strong, r < v.

Pleochroism (x):

bright yellowish pink.

Pleochroism (y):

reddish brown.

Pleochroism (z):

deep brownish red.

Reflectivity

**Standardized Intensity (100%) Reflection Spectra of Kentrolite in Air**
λ	R₁	R₂	∑ R₁(λ)	∑ R₂(λ)
400 nm	14.70	18.70
420 nm	14.40	18.10
440 nm	14.10	17.50
460 nm	13.90	16.90
480 nm	13.60	16.40
500 nm	13.40	16.00
520 nm	13.20	15.70
540 nm	13.00	15.40
560 nm	12.90	15.20
580 nm	12.80	15.00
600 nm	12.60	14.90
620 nm	12.50	14.80
640 nm	12.50	14.70
660 nm	12.40	14.50
680 nm	12.40	14.40
700 nm	12.30	14.30

**Calculated Relative Intensity Colors of Kentrolite in Air**
Relative Intensity	0%	70%	100%	140%	210%	280%	350%	420%	490%	560%	630%	690%
R₁
R₂

Calculated Properties of Kentrolite

Electron Density:

Bulk Density (Electron Density)=5.43 gm/cc
note: Specific Gravity of Kentrolite =6.25 gm/cc.

Fermion Index:

Fermion Index = 0.13
Boson Index = 0.87

Photoelectric:

PE_Kentrolite=1,013.97 barns/electron
U=PE_Kentrolite x rElectron Density=5,503.35 barns/cc.

Radioactivity:

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

Kentrolite Classification

Dana Class:

56.02.10.02 (56)Sorosilicate Si2O7 Groups and O, OH, F. and H2O

(56.02)with cations in [4] and/or >[4] coordination

(56.02.10)Melanotekite group

56.02.10.01 Melanotekite Pb2Fe2Si2O9 C 222₁ 2 2 2

56.02.10.02 Kentrolite Pb2Mn2Si2O9 P bcn 2/m 2/m 2/m

Strunz Class:

09.BE.80 09 - SILICATES (Germanates)

09.B - Sorosilicates

09.BE -Si2O7 groups with additional anions;

09.BE.80 Kentrolite Pb2Mn2Si2O9 P bcn 2/m 2/m 2/m

09.BE.80 Melanotekite Pb2Fe2Si2O9 C 222₁ 2 2 2

Other Kentrolite Information

References:

NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(AntBidBlaNic2)

See Also:

Links to other databases for Kentrolite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - Franklin Minerals(Dunn)
6 - Franklin Minerals(Palache)
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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Ask about Kentrolite here :
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Print or Cut-and-Paste your Kentrolite Specimen Label here :

Kentrolite

Pb2Mn+++2Si2O9
Dana No: 56.02.10.02 Strunz No: 09.BE.80
Locality:

Notes: