Olmiite
A valid IMA mineral species
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About Olmiite
Formula:
CaMn2+[SiO3(OH)](OH)
Colour:
Pale to intense reddish pink.
Lustre:
Vitreous
Hardness:
5 - 5½
Specific Gravity:
3.05
Crystal System:
Orthorhombic
Name:
Named for Filippo Olmi (1959-2005) who worked at CNR, Centro di Studio per la Minerogenesi e Geochimica Applicata, Florence, Italy.
Mn2+-dominant analogue of Poldervaartite.
A product of hydrothermal alteration.
Note: Most (all?) "poldervaartites" seem to be olmiites, see http://www.mindat.org/mesg-7-104499.html.
A product of hydrothermal alteration.
Note: Most (all?) "poldervaartites" seem to be olmiites, see http://www.mindat.org/mesg-7-104499.html.
Unique Identifiers
Mindat ID:
30762
Long-form identifier:
mindat:1:1:30762:6
Similar Names
IMA Classification of Olmiite
Approved
IMA Formula:
CaMn2+SiO3(OH)2
Approval year:
2006
First published:
2007
Type description reference:
Bonazzi, P., Bindi, L., Medenbach, O., Pagano, R., Lampronti, G. I., Menchetti, S. (2007) Olmiite, CaMn[SiO3(OH)](OH), the Mn-dominant analogue of poldervaartite, a new mineral species from Kalahari manganese fields (Republic of South Africa). Mineralogical Magazine, 71 (2). 193-201 doi:10.1180/minmag.2007.071.2.193
Classification of Olmiite
9.AF.90
9 : SILICATES (Germanates)
A : Nesosilicates
F : Nesosilicates with additional anions; cations in [4], [5] and/or only [6] coordination
9 : SILICATES (Germanates)
A : Nesosilicates
F : Nesosilicates with additional anions; cations in [4], [5] and/or only [6] coordination
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Olm | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Pronunciation of Olmiite
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Olmiite
Vitreous
Transparency:
Transparent
Colour:
Pale to intense reddish pink.
Streak:
White
Hardness:
5 - 5½ on Mohs scale
Tenacity:
Brittle
Cleavage:
None Observed
Fracture:
Irregular/Uneven
Density:
3.05 g/cm3 (Measured) 3.102 g/cm3 (Calculated)
Comment:
Calculated value based on unit cell volume; a value of 3.109 from powder data.
Optical Data of Olmiite
Type:
Biaxial (+)
RI values:
nα = 1.663(1) nβ = 1.672(1) nγ = 1.694(1)
2V:
Measured: 71° , Calculated: 66°
Max. Birefringence:
δ = 0.031
Based on recorded range of RI values above.
Based on recorded range of RI values above.
Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.
Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.
Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars. Each grain retains its interference colour (retardation) while its brightness falls to black at extinction and reaches a maximum between extinction positions.
Surface Relief:
Very High (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Interference Figure:
This shows the idealized biaxial acute bisectrix (Bxa) interference figure
- the conoscopic view for a grain cut perpendicular to the acute bisectrix, using
this mineral's 2V. The two small white dots mark the melatopes - the points
where the two optic axes emerge - and are shown only when they fall within the
field of view. The coloured bands are isochromatics, and the dark bands are
isogyres.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Rotate the stage: at 0°/90° the isogyres form a cross through the melatopes; at 45° they pull apart into curved hyperbolas. That splitting on rotation - absent in a uniaxial figure - is the standard diagnostic test for telling biaxial minerals from uniaxial ones. If 2V is large, the melatopes may fall outside the field of view, as they often do at the microscope too.
Dispersion:
r > v distinct
Pleochroism:
Non-pleochroic
Chemistry of Olmiite
Mindat Formula:
CaMn2+[SiO3(OH)](OH)
Element Weights:
Crystallography of Olmiite
Crystal System:
Orthorhombic
Class (H-M):
mmm(2/m2/m2/m) - Dipyramidal
Space Group:
Pbca
Cell Parameters:
a = 9.249 Å, b = 9.076 Å, c = 10.342 Å
Ratio:
a:b:c = 1.019 : 1 : 1.139
Unit Cell V:
868 ų
Z:
8
Morphology:
Crystals minute. Aggregates resemble wheat sheaves.
Crystal Structure
Load
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Unit Cell | Unit Cell Packed
2x2x2 | 3x3x3 | 4x4x4
Show
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Big Balls | Small Balls | Just Balls | Spacefill
Polyhedra Off | Si Polyhedra | All Polyhedra
Remove metal-metal sticks
Display Options
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
Black Background | White Background
Perspective On | Perspective Off
2D | Stereo | Red-Blue | Red-Cyan
View
CIF File Best | x | y | z | a | b | c
CIF File Best | x | y | z | a | b | c
Rotation
Stop | Start
Stop | Start
Labels
Console Off | On | Grey | Yellow
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0014579 | Olmiite | Bonazzi P, Bindi L, Medenbach O, Pagano R, Lampronti G I, Menchetti S (2007) Olmiite, CaMn[SiO3(OH)](OH), the Mn-dominant analogue of poldervaartite, a new mineral species from Kalahari manganese fields (Republic of South Africa) Mineralogical Magazine 71 193-201 | 2007 | N'Chwaning II mine, Republic of South Africa | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 4.14 Å | (60) |
| 4.10 Å | (30) |
| 3.19 Å | (100) |
| 2.807 Å | (35) |
| 2.762 Å | (30) |
| 2.545 Å | (35) |
| 2.521 Å | (30) |
| 2.361 Å | (40) |
Reference:
Bonazzi, P., Bindi, L., Medenbach, O., Pagano, R., Lampronti, G. I., Menchetti, S. (2007) Olmiite, CaMn[SiO3(OH)](OH), the Mn-dominant analogue of poldervaartite, a new mineral species from Kalahari manganese fields (Republic of South Africa). Mineralogical Magazine, 71 (2). 193-201 doi:10.1180/minmag.2007.071.2.193
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 22 : Hydration and low-? subsurface aqueous alteration (see also #23) |
Type Occurrence of Olmiite
General Appearance of Type Material:
Wheat sheaf aggregates.
Place of Conservation of Type Material:
Museo di Storia Naturale, Universita di Firenze, Italy, catalogue number 2987/I (holotype material).
Dipartimento di Scienze della Terra, Universita di Firenze, Italy.
Dipartimento di Scienze della Terra, Universita di Firenze, Italy.
Associated Minerals at Type Locality:
Reference:
Bonazzi, P., Bindi, L., Medenbach, O., Pagano, R., Lampronti, G. I., Menchetti, S. (2007) Olmiite, CaMn[SiO3(OH)](OH), the Mn-dominant analogue of poldervaartite, a new mineral species from Kalahari manganese fields (Republic of South Africa). Mineralogical Magazine, 71 (2). 193-201 doi:10.1180/minmag.2007.071.2.193
Synonyms of Olmiite
Other Language Names for Olmiite
Relationship of Olmiite to other Species
Forms a series with:
Common Associates
Associations Based on Photo Data:
| 207 photos of Olmiite associated with Calcite | CaCO3 |
| 159 photos of Olmiite associated with Bultfonteinite | Ca2(HSiO4)F · H2O |
| 58 photos of Olmiite associated with Oyelite | Ca10Si8B2O29 · 12.5H2O |
| 22 photos of Olmiite associated with Quartz | SiO2 |
| 19 photos of Olmiite associated with Xonotlite | Ca6(Si6O17)(OH)2 |
| 10 photos of Olmiite associated with Celestine | SrSO4 |
| 8 photos of Olmiite associated with Hematite | Fe2O3 |
| 7 photos of Olmiite associated with Goethite | Fe3+O(OH) |
| 6 photos of Olmiite associated with Manganite | Mn3+O(OH) |
| 6 photos of Olmiite associated with Poldervaartite | CaCa[SiO3(OH)](OH) |
Related Minerals - Strunz-mindat Grouping
| 9.AF. | Chegemite | Ca7(SiO4)3(OH)2 |
| 9.AF. | Jingwenite-(Y) | YAlV4+(SiO4)O2(OH)2 |
| 9.AF. | Barwoodite | Mn2+6Nb5+(SiO4)2O3(OH)3 |
| 9.AF.05 | Sillimanite | Al2(SiO4)O |
| 9.AF.05 | 'Xenolite' | Al10Si8O31 |
| 9.AF.10 | Kanonaite | Mn3+Al(SiO4)O |
| 9.AF.10 | Andalusite | Al2(SiO4)O |
| 9.AF.15 | Kyanite | Al2(SiO4)O |
| 9.AF.20 | Krieselite | Al2(GeO4)F2 |
| 9.AF.20 | Mullite | Al4+2xSi2-2xO10-x |
| 9.AF.23 | Boromullite | Al9BSi2O19 |
| 9.AF.25 | Yoderite | Mg(Al,Fe3+)3(SiO4)2O(OH) |
| 9.AF.30 | Zincostaurolite | Zn2Al9Si4O23(OH) |
| 9.AF.30 | Staurolite | Fe2+2Al9Si4O23(OH) |
| 9.AF.30 | Magnesiostaurolite | Mg(Mg,Li)3(Al,Mg)18Si8O44(OH)4 |
| 9.AF.35 | Topaz | Al2(SiO4)(F,OH)2 |
| 9.AF.40 | Norbergite | Mg3(SiO4)F2 |
| 9.AF.45 | Chondrodite | Mg5(SiO4)2F2 |
| 9.AF.45 | Kumtyubeite | Ca5(SiO4)2F2 |
| 9.AF.45 | Reinhardbraunsite | Ca5(SiO4)2(OH,F)2 |
| 9.AF.45 | Hydroxylchondrodite | Mg5(SiO4)2(OH)2 |
| 9.AF.45 | Alleghanyite | Mn2+5(SiO4)2(OH)2 |
| 9.AF.50 | 'Unnamed (Ca-analogue of Humite)' | Ca7(SiO4)4F2 |
| 9.AF.50 | Humite | Mg7(SiO4)3F2 |
| 9.AF.50 | Manganhumite | Mn2+7(SiO4)3(OH)2 |
| 9.AF.50 | 'Unnamed (OH-analogue of humite)' | Mg7(SiO4)3(OH)2 |
| 9.AF.50 | Fluorchegemite | Ca7(SiO4)3F2 |
| 9.AF.55 | Hydroxylclinohumite | Mg9(SiO4)4(OH)2 |
| 9.AF.55 | Clinohumite | Mg9(SiO4)4F2 |
| 9.AF.55 | Sonolite | Mn2+9(SiO4)4(OH)2 |
| 9.AF.60 | Leucophoenicite | Mn2+7(SiO4)3(OH)2 |
| 9.AF.65 | Ribbeite | Mn2+5(SiO4)2(OH)2 |
| 9.AF.70 | Jerrygibbsite | Mn2+9(SiO4)4(OH)2 |
| 9.AF.75 | Franciscanite | Mn2+6(V5+,◻)2(SiO4)2(O,OH)6 |
| 9.AF.75 | Scorticoite | Mn6(Sb,◻)Σ2(SiO4)2O3(OH)3 |
| 9.AF.75 | Welinite | Mn2+6(W6+,Mg)2(SiO4)2(O,OH)6 |
| 9.AF.75 | Örebroite | Mn2+3(Sb5+,Fe3+)(SiO4)(O,OH)3 |
| 9.AF.80 | Ellenbergerite | Mg6(Mg,Ti,Zr,◻)2(Al,Mg)6Si8O28(OH)10 |
| 9.AF.85 | Magnesiochloritoid | MgAl2O(SiO4)(OH)2 |
| 9.AF.85 | Ottrélite | Mn2+Al2O(SiO4)(OH)2 |
| 9.AF.85 | Chloritoid | Fe2+Al2O(SiO4)(OH)2 |
| 9.AF.90 | Poldervaartite | CaCa[SiO3(OH)](OH) |
| 9.AF.95 | Pilawite-(Y) | Ca2Y2Al4(SiO4)4O2(OH)2 |
Fluorescence of Olmiite
Deep red (SW UV)
Other Information
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Olmiite
mindat.org URL:
https://www.mindat.org/min-30762.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Olmiite
Reference List:
Bonazzi, P., Bindi, L., Medenbach, O., Pagano, R., Lampronti, G. I., Menchetti, S. (2007) Olmiite, CaMn[SiO3(OH)](OH), the Mn-dominant analogue of poldervaartite, a new mineral species from Kalahari manganese fields (Republic of South Africa). Mineralogical Magazine, 71 (2). 193-201 doi:10.1180/minmag.2007.071.2.193
Cook, Robert B. (2012) Connoisseur's Choice: Olmiite, N'Chwaning II Mine, Kalahari Manganese Field, Republic of South Africa. Rocks & Minerals, 87 (2) 150-155 doi:10.1080/00357529.2012.657988
Frost, Ray L., Scholz, Ricardo, López, Andrés, Xi, Yunfei, Granja, Amanda, Žigovečki Gobac, Željka, Lima, Rosa Malena Fernandes (2013) Infrared and Raman spectroscopic characterization of the silicate mineral olmiite CaMn2+[SiO3(OH)](OH) – implications for the molecular structure. Journal of Molecular Structure, 1053. 22-26 doi:10.1016/j.molstruc.2013.08.038
Localities for Olmiite
Showing 5 localities.
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
South Africa (TL) | |
| Bonazzi et al. (2007) |
| P.Rondelez | |
| www.mindat.org (2009) | |
Spain | |
| Dill et al. (2023) |
Sweden | |
|
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N'Chwaning II Mine, N'Chwaning Mines, Joe Morolong Local Municipality, John Taolo Gaetsewe District Municipality, Northern Cape, South Africa