Okayamalite
A valid IMA mineral species
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Formula:
Ca2B[BSiO7]
Colour:
cream white
Lustre:
Earthy
Hardness:
5½
Specific Gravity:
3.30 (Calculated)
Crystal System:
Tetragonal
Member of:
Name:
Named after Okayama Prefecture, Japan, which includes the type locality.
This page provides mineralogical data about Okayamalite.
Unique Identifiers
Mindat ID:
7202
Long-form identifier:
mindat:1:1:7202:7
GUID
(UUID V4):
(UUID V4):
21b26b33-91bf-4290-89c1-4d0997994785
IMA Classification of Okayamalite
Approved
IMA Formula:
Ca2B2SiO7
Approval year:
1997
First published:
1998
Classification of Okayamalite
9.BB.10
9 : SILICATES (Germanates)
B : Sorosilicates
B : Si2O7 groups, without non-tetrahedral anions; cations in tetrahedral [4] and greater coordination
9 : SILICATES (Germanates)
B : Sorosilicates
B : Si2O7 groups, without non-tetrahedral anions; cations in tetrahedral [4] and greater 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 |
---|---|---|
Oky | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Okayamalite
Earthy
Transparency:
Translucent
Colour:
cream white
Streak:
white
Hardness:
5½ on Mohs scale
Cleavage:
None Observed
Density:
3.30 g/cm3 (Calculated)
Optical Data of Okayamalite
Type:
Uniaxial (-)
RI values:
nω = 1.700 nε = 1.696
Max Birefringence:
δ = 0.004
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
and does not take into account mineral colouration.
Surface Relief:
High
Chemistry of Okayamalite
Mindat Formula:
Ca2B[BSiO7]
Elements listed:
Crystallography of Okayamalite
Crystal System:
Tetragonal
Class (H-M):
4 2m - Scalenohedral
Space Group:
P4 21m
Cell Parameters:
a = 7.1248(2) Å, c = 4.8177(2) Å
Ratio:
a:c = 1 : 0.676
Unit Cell V:
244.56 ų (Calculated from Unit Cell)
Z:
2
Crystal Structure
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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) |
---|---|---|---|---|---|---|---|
0002589 | Okayamalite | Giuli G, Bindi L, Bonazzi P (2000) Rietveld refinement of okayamalite, Ca2SiB2O7: Structural evidence for the B/Si ordered distribution American Mineralogist 85 1512-1515 | 2000 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
d-spacing | Intensity |
---|---|
2.654 Å | (100) |
2.862 Å | (55) |
3.479 Å | (40) |
1.920 Å | (35) |
1.644 Å | (29) |
2.129 Å | (20) |
1.644 Å | (20) |
Geological Environment
Paragenetic Mode(s):
Paragenetic Mode | Earliest Age (Ga) |
---|---|
Near-surface Processes | |
23 : Subaerial aqueous alteration by non-redox-sensitive fluids (see also #47) |
Type Occurrence of Okayamalite
General Appearance of Type Material:
grains to 10 μm in equigranular aggregates
Place of Conservation of Type Material:
National Science Museum, Tokyo, under the registered number NSM M-27525.
Associated Minerals at Type Locality:
Reference:
Matsubara, S., Miyawaki, R., Kato, A., Yokoyama, K., Okamoto, A. (1998) Okayamalite, Ca2B2SiO7, a new mineral, boron analogue of gehlenite. Mineralogical Magazine: 62: 703-706.
Synonyms of Okayamalite
Other Language Names for Okayamalite
Relationship of Okayamalite to other Species
Member of:
Other Members of this group:
Åkermanite | Ca2Mg[Si2O7] | Tet. 4 2m : P4 21m |
Alumoåkermanite | (CaNa)Al[Si2O7] | Tet. 4 2m : P4 21m |
Bennesherite | Ba2Fe2+[Si2O7] | Tet. 4 2m : P4 21m |
Ferri-gehlenite | Ca2Fe3+[AlSiO7] | |
Gehlenite | Ca2Al[AlSiO7] | Tet. 4 2m : P4 21m |
Gugiaite | Ca2Be[Si2O7] | Tet. 4 2m : P4 2m |
Hardystonite | Ca2Zn[Si2O7] | Tet. 4 2m : P4 21m |
Hydroxylgugiaite | (Ca,◻)2(Si,Be)[(Be,Si)2O5.5(OH)1.5] | Tet. 4 2m : P4 21m |
Related Minerals - Strunz-mindat Grouping
9.BB.10 | Åkermanite | Ca2Mg[Si2O7] |
9.BB.10 | Cebollite | Ca5Al2(SiO4)3(OH)4 |
9.BB.10 | Gehlenite | Ca2Al[AlSiO7] |
9.BB.10 | Gugiaite | Ca2Be[Si2O7] |
9.BB.10 | Hardystonite | Ca2Zn[Si2O7] |
9.BB.10 | Jeffreyite | (Ca,Na)2(Be,Al)(Si2O7,HSi2O7) |
9.BB.10 | Ferri-gehlenite | Ca2Fe3+[AlSiO7] |
9.BB.10 | Alumoåkermanite | (CaNa)Al[Si2O7] |
9.BB.10 | Hydroxylgugiaite | (Ca,◻)2(Si,Be)[(Be,Si)2O5.5(OH)1.5] |
9.BB.15 | Barylite | Be2Ba(Si2O7) |
9.BB.15 | Barylite-1O | Be2Ba(Si2O7) |
9.BB.20 | Andrémeyerite | BaFe2+2(Si2O7) |
9.BB.20 | Bennesherite | Ba2Fe2+[Si2O7] |
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 Okayamalite
mindat.org URL:
https://www.mindat.org/min-7202.html
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References for Okayamalite
Reference List:
Matsubara, Satoshi, Miyawaki, Ritsuro, Kato, Akira, Yokoyama, Kazumi, Okamoto, Akiyoshi (1998) Okayamalite, Ca2B2SiO7, a new mineral, boron analogue of gehlenite. Mineralogical Magazine, 62 (5) 703-706 doi:10.1180/002646198547936
Olmi, F., Viti, C., Bindi, L., Bonazzi, P., Menchetti, S. (2000) Second occurrence of okayamalite, Ca2SiB2O7: chemical and TEM characterization. American Mineralogist, 85 (10) 1508-1511 doi:10.2138/am-2000-1022
Localities for Okayamalite
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).
Struck out - Mineral was erroneously reported from this locality.
Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).
All localities listed without proper references should be considered as questionable.
All localities listed without proper references should be considered as questionable.
Japan (TL) | |
| Matsubara et al. (1998) |
Norway | |
| Olmi et al. (2000) +1 other reference |
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