Mineralogy Database

Okayamalite Mineral Data

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General Okayamalite Information

Help on Chemical  Formula: Chemical Formula: Ca2B2SiO7
Help on Composition: Composition: Molecular Weight = 241.86 gm
   Calcium  33.14 %  Ca   46.37 % CaO
   Silicon  11.61 %  Si   24.84 % SiO2
   Boron     8.94 %  B    28.78 % B2O3
   Oxygen   46.31 %  O
           ______        ______ 
           100.00 %      100.00 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: Ca2B2SiO7
Help on Environment: Environment: The boron-dominant analogue of gehlenite. Skarn mineral probably formed by the desilication-dehydroxylation of datolite.
Help on IMA Status: IMA Status: Approved IMA 1998 (Dana # Added)
Help on Locality: Locality: The Fuka mine, Bicchu-cho, Okayama Prefecture, Japan. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named after it's locality.
Help on Name Pronunciation: Name Pronunciation: Okayamalite + Pronunciation Say OKAYAMALITE
Help on Synonym: Synonym: ICSD 89739

Okayamalite Image

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Comments: Intergrowth between crystalline okayamalite (a) and amorphous silica (b). Okayamalite here forms regular lamellae elongated along [001], typically 400 Ã… thick. The grainy area (c) corresponds to the graphite film..
Location: Skarn sample from the Arendal district, Sorlandet, Norway. (AmMin, v85:1508). Scale: See Image.
© American Mineralogist

Okayamalite Crystallography

Help on Axial Ratios: Axial Ratios: a:c = 1:0.67664
Help on Cell Dimensions: Cell Dimensions: a = 7.116, c = 4.815, Z = 2; V = 243.82 Den(Calc)= 3.29
Help on Crystal System: Crystal System: Tetragonal - Scalenohedral H-M Symbol (4 2m) Space Group: P 421m
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 2.655(1), 2.862(0.56), 3.479(0.4),1.92(0.35), 1.644(0.2), 2.128(0.2), 2.23(0.15), 1.726(0.1), 2.25(0.1),

Physical Properties of Okayamalite

Help on Cleavage: Cleavage: None
Help on Color: Color: Creamy white.
Help on Density: Density: 3.3
Help on Habit: Habit: Microscopic Crystals - Crystals visible only with microscopes.
Help on Hardness: Hardness: 5.5 - Knife Blade
Help on Luster: Luster: Earthy (Dull)
Help on Streak: Streak: white

Optical Properties of Okayamalite

Help on Gladstone-Dale: Gladstone-Dale: CI meas= 0.016 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.013 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2082,KPDmeas= 0.2076,KC= 0.2109
Ncalc = 1.69 - 1.7
Help on Optical Data: Optical Data: Uniaxial (-), e=1.67, w=1.7, bire=0.0300.

Calculated Properties of Okayamalite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=3.26 gm/cc
note: Specific Gravity of Okayamalite =3.29 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.02
Boson Index = 0.98
Help on Photoelectric: Photoelectric: PEOkayamalite = 4.63 barns/electron
U=PEOkayamalite x rElectron Density= 15.11 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Okayamalite is Not Radioactive

Okayamalite Classification

Help on  Dana Class: Dana Class: (55)Sorosilicate Si2O7 Groups, Generally with No Additional Anions
  (55.04)with cations in [8] and lower coordination
  (55.04.01)Melilite group Akermanite Ca2MgSi2O7 P 421m 4 2m Gehlenite Ca2Al(AlSi)O7 P 421m 4 2m Melilite (Ca,Na)2(Al,Mg,Fe)(Si,Al)2O7 P 421m 4 2m Okayamalite! Ca2B2SiO7 P 421m 4 2m Alumoakermanite! (Ca,Na)2(Al,Mg,Fe)(Si2O7) P 421m 4 2m
Help on  Strunz Class: Strunz Class: 09.BB.10 09 - SILICATES (Germanates)
  09.B - Sorosilicates
  09.BB -Si2O7 groups, without non-tetrahedral anions;
09.BB.10 Akermanite Ca2MgSi2O7 P 421m 4 2m
09.BB.10 Cebollite Ca5Al2(SiO4)3(OH)4 Unk Ortho
09.BB.10 Gugiaite Ca2BeSi2O7 P 421m 4 2m
09.BB.10 Gehlenite Ca2Al(AlSi)O7 P 421m 4 2m
09.BB.10 Jeffreyite (Ca,Na)2(Be,Al)Si2(O,OH)7 C 2221 2 2 2
09.BB.10 Hardystonite Ca2ZnSi2O7 P 421m 4 2m
09.BB.10 Melilite (Ca,Na)2(Al,Mg,Fe)(Si,Al)2O7 P 421m 4 2m
09.BB.10 Okayamalite! Ca2B2SiO7 P 421m 4 2m

Other Okayamalite Information

Help on References: References: NAME( MinRec) PHYS. PROP.(Eur. J. Min.,Vol.10,1998) OPTIC PROP.(MinRec)
Help on See Also: See Also: Links to other databases for Okayamalite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - GeoScienceWorld
4 - Google Images
5 - Google Scholar
6 - MinDAT
7 - Mineralienatlas (Deutsch)
8 - Online Mineral Museum
9 - QUT Mineral Atlas
10 - Ruff.Info

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Dana No: Strunz No: 09.BB.10





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