Koashvite Mineral Data

General Koashvite Information

Chemical Formula:

Na6(Ca,Mn)(Ti,Fe)Si6O18•(H2O)

Composition:

Molecular Weight = 711.83 gm

Sodium 19.38 % Na 26.12 % Na₂O

Calcium 2.82 % Ca 3.94 % CaO

Titanium 3.36 % Ti 5.61 % TiO₂

Manganese 3.86 % Mn 4.98 % MnO

Iron 3.92 % Fe 5.61 % Fe₂O₃

Silicon 23.67 % Si 50.65 % SiO₂

Hydrogen 0.28 % H 2.53 % H₂O

Oxygen 42.71 % O

______ ______

100.00 % 99.44 % = TOTAL OXIDE

Empirical Formula:

Na₆Ca_0.5Mn²⁺_0.5Ti_0.5Fe³⁺_0.5Si₆O₁₈•(H₂O)

Environment:

In alkalic pegmatites.

IMA Status:

Approved IMA 1974

Locality:

Mt. Koashva, Khibiny massif, Kola, Peninsula, Russia. Link to MinDat.org Location Data.

Name Origin:

Named for the locality.

Name Pronunciation:

Koashvite + Pronunciation

Synonym:

ICSD 86517

PDF 27-669

Koashvite Image

Images:

Koashvite

Comments: Brown translucent crystalline fragment of koashvite.
Location: Mount Koashva, Khibiny Massive, Kola Peninsula, Murmansk District, Russia. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Koashvite Crystallography

Axial Ratios:

a:b:c =0.3511:1:0.4865

Cell Dimensions:

a = 7.356, b = 20.95, c = 10.194, Z = 4; V = 1,570.98 Den(Calc)= 3.01

Crystal System:

Orthorhombic - Dipyramidal H-M Symbol (2/m 2/m 2/m) Space Group: Pmnb

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

By Intensity(I/I_o): 2.581(1), 1.82(0.7), 3.66(0.5),

Physical Properties of Koashvite

Cleavage:

None

Color:

Brownish yellow, Light yellow.

Density:

2.98 - 3.02, Average = 3

Diaphaneity:

Transparent

Fracture:

Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).

Hardness:

6 - Orthoclase

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Koashvite

Gladstone-Dale:

CI meas= 0.032 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= 0.036 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2135,KPDmeas= 0.2142,KC= 0.2214
Ncalc = 1.66 - 1.67

Optical Data:

Biaxial (-), a=1.637, b=1.643, g=1.648, bire=0.0110, 2V(Calc)=84, 2V(Meas)=82-84. Dispersion weak, r > v.

Calculated Properties of Koashvite

Electron Density:

Bulk Density (Electron Density)=2.95 gm/cc
note: Specific Gravity of Koashvite =3.00 gm/cc.

Fermion Index:

Fermion Index = 0.01
Boson Index = 0.99

Photoelectric:

PE_Koashvite= 4.25 barns/electron
U=PE_Koashvite x rElectron Density= 12.55 barns/cc.

Radioactivity:

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

Koashvite Classification

Dana Class:

61.01.02b.02 (61)Cyclosilicate Six-Membered Rings

(61.01)with [Si6O18] rings; possible (OH) and Al substitution

(61.01.02b)Lovozerite group (Ortho and MON subgroup)

61.01.02b.01 Imandrite Na12Ca3Fe2Si12O36 Pnnm 2/m 2/m 2/m

61.01.02b.02 Koashvite Na6(Ca,Mn)(Ti,Fe)Si6O18•(H2O) Pmnb 2/m 2/m 2/m

61.01.02b.03 Petarasite Na5Zr2Si6O18(Cl,OH)•2(H2O) P 2₁/m 2/m

61.01.02b.04 Litvinskite! Na2([],Na,Mn)Zr[Si6O12(OH,O)6] Cm m

Strunz Class:

09.CJ.20 09 - SILICATES (Germanates)

09.C - Cyclosilicates

09.CJ -[Si6O18]12- 6-membered single rings (sechser-Einfachringe),

09.CJ.20 Koashvite Na6(Ca,Mn)(Ti,Fe)Si6O18•(H2O) Pmnb 2/m 2/m 2/m

09.CJ.20 Imandrite Na12Ca3Fe2Si12O36 Pnnm 2/m 2/m 2/m

Other Koashvite Information

References:

NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Dana8)

See Also:

Links to other databases for Koashvite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info

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

Koashvite

Na6(Ca,Mn)(Ti,Fe)Si6O18•(H2O)
Dana No: 61.01.02b.02 Strunz No: 09.CJ.20
Locality:

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