Olmiite Mineral Data

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General Olmiite Information

Chemical Formula:

CaMn[SiO3(OH)](OH)

Composition:

Molecular Weight = 203.44 gm

Calcium 22.65 % Ca 31.70 % CaO

Manganese 22.95 % Mn 29.64 % MnO

Iron 0.27 % Fe 0.35 % FeO

Silicon 13.81 % Si 29.53 % SiO₂

Hydrogen 0.99 % H 8.86 % H₂O

Oxygen 39.32 % O

______ ______

100.00 % 100.08 % = TOTAL OXIDE

Empirical Formula:

Ca_1.15Mn²⁺_0.85Fe²⁺_0.01(SiO₃)(OH)₂

Environment:

Mn-dominant analogue of poldervaartite

IMA Status:

Approved IMA 2006 (Dana # Added)

Locality:

N’Chwaning II mine, Kalahari field, Republic of South Africa Link to MinDat.org Location Data.

Name Origin:

Named for Filippo Olmi, mineralogist at Centre di Studio per la Minerogenesi ela Geochimica Applicata, Florence, Italy

Synonym:

IMA2006-026

Olmiite Image

Images:

Olmiite

Comments: Spherical aggregate of prismatic crystals of pinkish tan olmiite..
Location: N'chwaning II Mine, section 5 south stope, 46-47 roof, Kuruman South Africa. Scale: Specimen size 2.5 × 2 × 1.4 cm.
© Fabre Minerals

Olmiite Crystallography

Axial Ratios:

a:b:c =1.019:1:1.1394

Cell Dimensions:

a = 9.249, b = 9.076, c = 10.342, Z = 8; V = 868.15 Den(Calc)= 3.11

Crystal System:

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

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

By Intensity(I/I_o): 3.19(1), 4.14(0.6), 2.361(0.4),2.545(0.35), 2.807(0.35), 2.521(0.3), 2.762(0.3),

Crystal Structure:

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Bonazzi P , Bindi L , Medenbach O , Pagano R , Lampronti G I , Menchetti S , Mineralogical Magazine , 71 (2007) p.193-201, Olmiite, CaMn[SiO3(OH)](OH), the Mn-dominant analogue of poldervaartite,, a new mineral species from Kalahari manganese fields (Republic of South Africa), Locality: N Chwaning II mine, Republic of South Africa

Physical Properties of Olmiite

Cleavage:

None

Color:

Reddish pink.

Density:

3.05

Diaphaneity:

Transparent

Fracture:

Brittle - Irregular - Very brittle fracture producing irregular fragments

Habit:

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

Hardness:

5-5.5 - Apatite-Knife Blade

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Olmiite

Gladstone-Dale:

CI meas= -0.021 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= -0.001 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2175,KPDmeas= 0.2217,KC= 0.2172
Ncalc = 1.66 - 1.68

Optical Data:

Biaxial (+), a=1.663, b=1.672, g=1.694, bire=0.0310, 2V(Calc)=66, 2V(Meas)=71.8. Dispersion r > v.

Calculated Properties of Olmiite

Electron Density:

Bulk Density (Electron Density)=3.07 gm/cc
note: Specific Gravity of Olmiite =3.11 gm/cc.

Fermion Index:

Fermion Index = 0.0070012151
Boson Index = 0.9929987849

Photoelectric:

PE_Olmiite= 9.18 barns/electron
U=PE_Olmiite x rElectron Density= 28.22 barns/cc.

Radioactivity:

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

Olmiite Classification

Dana Class:

78.01.08.02 (78)Unclassified silicates

(78.01)possible nesosilicates

(78.01.08)Dana Group

78.01.08.01 Poldervaartite (Ca,Mn)2SiO3(OH)2 P bca 2/m 2/m 2/m

78.01.08.02 Olmiite! CaMn[SiO3(OH)](OH) P bca 2/m 2/m 2/m

Strunz Class:

09.AF.90 09 - SILICATES (Germanates)

09.A - Nesosilicates

09.AF -Nesosilicates with additional anions;

09.AF.90 Poldervaartite (Ca,Mn)2SiO3(OH)2 P bca 2/m 2/m 2/m

09.AF.90 Olmiite! CaMn[SiO3(OH)](OH) P bca 2/m 2/m 2/m

Other Olmiite Information

References:

NAME( EurJMin, v71:193) PHYS. PROP.(EurJMin, v71:193) OPTIC PROP.(EurJMin, v71:193)

See Also:

Links to other databases for Olmiite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - Google Images
4 - Google Scholar
5 - MinDAT
6 - MinMax(Deutsch)
7 - MinMax(English)
8 - Mineralienatlas (Deutsch)
9 - QUT Mineral Atlas
10 - Ruff.Info

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

Olmiite

CaMn[SiO3(OH)](OH)
Dana No: 78.01.08.02 Strunz No: 09.AF.90
Locality:

Notes: