Ribbeite Mineral Data

Ribbeite Mineral Data +

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General Ribbeite Information

Chemical Formula:

(Mn++,Mg)5(SiO4)2(OH)2

Composition:

Molecular Weight = 454.58 gm

Magnesium 6.68 % Mg 11.08 % MgO

Manganese 45.32 % Mn 58.52 % MnO

Silicon 12.36 % Si 26.44 % SiO₂

Hydrogen 0.44 % H 3.96 % H₂O

Oxygen 35.20 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Mn²⁺_3.75Mg_1.25(SiO₄)₂(OH)₂

Environment:

Polymorph of allegehanyite.

IMA Status:

Approved IMA 1987

Locality:

E15-11 South stope, 11 level, 1241 elevation, in the Asis West sector of the Kombat mine, located 37 km east of Otavi and 49 km south of Tsumeb in the north-central part of Namibia. Link to MinDat.org Location Data.

Name Origin:

Named for Paul Ribbe of Virginia Polytechnical Institute and State University.

Synonym:

ICSD 66646

PDF 40-491

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Ribbeite Crystallography

Axial Ratios:

a:b:c =0.6847:1:0.3069

Cell Dimensions:

a = 10.732, b = 15.672, c = 4.811, Z = 4; V = 809.17 Den(Calc)= 3.73

Crystal System:

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

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

By Intensity(I/I_o): 1.796(1), 2.552(0.8), 2.873(0.8),

Crystal Structure:

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Freed R L , Rouse R C , Peacor D R , American Mineralogist , 78 (1993) p.190-194, Ribbeite, a second example of edge-sharing silicate tetrahedra in the, leucophoenicite group

Physical Properties of Ribbeite

Cleavage:

None

Color:

Pink.

Density:

3.9

Diaphaniety:

Transparent

Hardness:

5 - Apatite

Luster:

Vitreous (Glassy)

Streak:

light pink

Optical Properties of Ribbeite

Gladstone-Dale:

CI meas= 0.012 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.033 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2127,KPDmeas= 0.2034,KC= 0.2059

Optical Data:

Biaxial (+), a=1.78, b=1.792, g=1.808, bire=0.0280, 2V(Calc)=84, 2V(Meas)=83.

Calculated Properties of Ribbeite

Electron Density:

r_electron=3.75 gm/cc
note: r_Ribbeite=3.90 gm/cc.

Fermion Index

Fermion Index = 0.01262
Boson Index = 0.98738

Photoelectric:

PE_Ribbeite= 12.27 barns/electron
U=PE_Ribbeite x r_electron= 46.06 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Ribbeite is Not Radioactive

Ribbeite Classification

Dana Class:

52.3.2b.4 (52)Nesosilicate Insular SiO4 Groups and O, OH, F, and H2O

(52.3)with cations in [6] coordination only

(52.3.2b)Humite group (Chondrodite series)

52.3.2b.1 Alleghanyite Mn5(SiO4)2(OH)2 P 2₁/a 2/m

52.3.2b.2 Chondrodite (Mg,Fe)5(SiO4)2(F,OH)2 P 2₁/c 2/m

52.3.2b.3 Reinhardbraunsite Ca5(SiO4)2(OH,F)2 P 2₁/a 2/m

52.3.2b.4 Ribbeite (Mn,Mg)5(SiO4)2(OH)2 P nma 2/m 2/m 2/m

Strunz Class:

VIII/B.04-50 VIII - Silicates

VIII/B - Nesosubsilicates, with anions unfamiliar to tetraheders, cations of octahedral and tetrahedral orientation [4/6]

VIII/B.04 - Humite group

VIII/B.04-10 Norbergite Mg3(SiO4)(F,OH)2 P nma 2/m 2/m 2/m

VIII/B.04-20 Chondrodite (Mg,Fe)5(SiO4)2(F,OH)2 P 2₁/c 2/m

VIII/B.04-30 Humite (Mg,Fe)7(SiO4)3(F,OH)2 P nma 2/m 2/m 2/m

VIII/B.04-40 Clinohumite (Mg,Fe)9(SiO4)4(F,OH)2 P 2₁/c 2/m

VIII/B.04-42 Hydroxylclinohumite! Mg9(SiO4)4(OH,F)2 P 2₁/c 2/m

VIII/B.04-50 Ribbeite (Mn,Mg)5(SiO4)2(OH)2 P nma 2/m 2/m 2/m

VIII/B.04-60 Alleghanyite Mn5(SiO4)2(OH)2 P 2₁/a 2/m

VIII/B.04-70 Reinhardbraunsite Ca5(SiO4)2(OH,F)2 P 2₁/a 2/m

VIII/B.04-80 Manganhumite (Mn,Mg)7(SiO4)3(OH)2 Pbnm 2/m 2/m 2/m

VIII/B.04-90 Leucophoenicite Mn7(SiO4)3(OH)2 P 2₁/a 2/m

VIII/B.04-100 Jerrygibbsite (Mn,Zn)9(SiO4)4(OH)2 Pbn21 mm2

VIII/B.04-110 Sonolite Mn9(SiO4)4(OH,F)2 P 2₁/a 2/m

Other Ribbeite Information

References:

NAME( MinRec, v 22, pa 422) PHYS. PROP.(Am.Min.,Vol.72,p213-216,1987) OPTIC PROP.(Am.Min.,Vol.72,p213-216,1987)

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

Ribbeite

(Mn++,Mg)5(SiO4)2(OH)2
Dana No: 52.3.2b.4 Strunz No: VIII/B.04-50
Locality:

Notes: