Bementite Mineral Data

Bementite Mineral Data +

General Bementite Information

Chemical Formula:

Mn8Si6O15(OH)10

Composition:

Molecular Weight = 1,018.08 gm

Manganese 43.17 % Mn 55.74 % MnO

Silicon 16.55 % Si 35.41 % SiO₂

Hydrogen 0.99 % H 8.85 % H₂O

Oxygen 39.29 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Mn²⁺₈Si₆O₁₅(OH)₁₀

Environment:

Metamorphosed zinc deposit.

IMA Status:

Approved IMA 1963

Locality:

Franklin, Sussex Co., New Jersey. USA. Link to MinDat.org Location Data.

Name Origin:

For Clarence Sweet Bement (1843-1923), mineral collector of Philadelphia, Pennsylvania, USA.

Bementite Image

Images:

Bementite

Comments: Brown massive bementite.
Location: Olympic Mountains, Washington, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Bementite Crystallography

Axial Ratios:

a:b:c =0.8438:1:0.8359

Cell Dimensions:

a = 14.838, b = 17.584, c = 14.7, Z = 7; beta = 95.54° V = 3,817.48 Den(Calc)= 3.10

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: P 2₁/c

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

By Intensity(I/I_o): 7.3(1), 2.51(0.9), 2.81(0.7),

Crystal Structure:

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Heinrich A R , Eggleton R A , Guggenheim S , American Mineralogist , 79 (1994) p.91-106, Structure and polytypism of bementite, a modulated layer silicate

Physical Properties of Bementite

Cleavage:

[???] Perfect, [???] Good, [???] Good

Color:

Brown, Gray, Yellow, Yellow brown, Pink.

Density:

2.98

Diaphaniety:

Translucent to subtranslucent

Habit:

Massive - Uniformly indistinguishable crystals forming large masses.

Habit:

Radial - Crystals radiate from a center without producing stellar forms (e.g. stibnite)

Hardness:

6 - Orthoclase

Luminescence:

Non-fluorescent.

Luster:

Vitreous (Glassy)

Magnetism:

Nonmagnetic

Streak:

yellow white

Optical Properties of Bementite

Gladstone-Dale:

CI meas= 0.007 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.046 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2038,KPDmeas= 0.212,KC= 0.2135

Optical Data:

Biaxial (?), a=1.602-1.624, b=1.632-1.65, g=1.632-1.65, bire=0.0260-0.0300

Calculated Properties of Bementite

Electron Density:

r_electron=2.89 gm/cc
note: r_Bementite=2.98 gm/cc.

Fermion Index

Fermion Index = 0.00791
Boson Index = 0.99209

Photoelectric:

PE_Bementite= 11.66 barns/electron
U=PE_Bementite x r_electron= 33.72 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Bementite is Not Radioactive

Bementite Classification

Dana Class:

78.5.2.1 (78)Unclassified silicates

(78.5)possible phyllosilicates

(78.5.2)Dana Group

78.5.2.1 Bementite Mn8Si6O15(OH)10 P 2₁/c 2/m

Strunz Class:

VIII/H.28-90 VIII - Silicates

VIII/H - Phyllosilicates (layered) Mica minerals with other simple layers, [Si6O15]6- and others

VIII/H.28 - Pyrosmalite series

VIII/H.28-10 Ferropyrosmalite (Fe,Mn)8Si6O15(OH,Cl)10 P 3m1 3 2/m

VIII/H.28-20 Manganpyrosmalite (Mn,Fe)8Si6O15(OH,Cl)10 P 3m1 3 2/m

VIII/H.28-30 Brokenhillite* (Mn,Fe)32[Si24O60]OH29Cl11 P 6₃mc 6mm

VIII/H.28-40 Nelenite (Mn,Fe)16Si12As3O36(OH)17 R 3m 3 2/m

VIII/H.28-50 Schallerite Mn16[AsO2OH][Si12O30](OH)14 P 3m1 ? 3m

VIII/H.28-70 Friedelite Mn8Si6O15(OH,Cl)10 C 2/m 2/m

VIII/H.28-80 Mcgillite (Mn,Fe)8Si6O15(OH)8Cl2 C 2/m 2/m

VIII/H.28-90 Bementite Mn8Si6O15(OH)10 P 2₁/c 2/m

VIII/H.28-100 Varennesite Na8Mn2Si10O25(OH,Cl)2·12(H2O) C mcm 2/m 2/m 2/m

Other Bementite Information

References:

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

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Bementite

Mn8Si6O15(OH)10
Dana No: 78.5.2.1 Strunz No: VIII/H.28-90
Locality:

Notes: