Koashvite Mineral Data

Koashvite Mineral Data +

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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.

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 - DipyramidalH-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

Diaphaniety:

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

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:

r_electron=2.95 gm/cc
note: r_Koashvite=3.00 gm/cc.

Fermion Index

Fermion Index = 0.01647
Boson Index = 0.98353

Photoelectric:

PE_Koashvite= 4.25 barns/electron
U=PE_Koashvite x r_electron= 12.55 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Koashvite is Not Radioactive

Koashvite Classification

Dana Class:

61.1.2b.2 (61)Cyclosilicate Six-Membered Rings

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

(61.1.2b)Lovozerite group (Ortho and MON subgroup)

61.1.2b.1 Imandrite Na12Ca3Fe2Si12O36 Pnnm 2/m 2/m 2/m

61.1.2b.2 Koashvite Na6(Ca,Mn)(Ti,Fe)Si6O18·(H2O) Pmnb 2/m 2/m 2/m

61.1.2b.3 Petarasite Na5Zr2Si6O18(Cl,OH)·2(H2O) P 2₁/m 2/m

61.1.2b.4 Litvinskite! Na2([],Na,Mn)Zr[Si6O12(OH,O)6] Cm m

Strunz Class:

VIII/E.16-50 VIII - Silicates

VIII/E - Cyklosilicates, six rings [Si6O18]12-

VIII/E.16 - Lovozerite group

VIII/E.16-10 Imandrite Na12Ca3Fe2Si12O36 Pnnm 2/m 2/m 2/m

VIII/E.16-20 Kazakovite Na6MnTiSi6O18 R 3m 3 2/m

VIII/E.16-23 Kapustinite! Na5.5Mn0.25ZrSi6O16(OH)2 C 2/m 2/m

VIII/E.16-25 Litvinskite! Na2([],Na,Mn)Zr[Si6O12(OH,O)6] Cm m

VIII/E.16-30 Lovozerite H4Na2Ca(Zr,Ti)[Si6O18] R 3m 3 2/m

VIII/E.16-40 Zirsinalite Na6(Ca,Mn,Fe)Zr[Si6O18] R 3m 3 2/m

VIII/E.16-50 Koashvite Na6(Ca,Mn)(Ti,Fe)Si6O18·(H2O) Pmnb 2/m 2/m 2/m

VIII/E.16-60 Tisinalite Na3H3(Mn,Ca,Fe)TiSi6(O,OH)18·2(H2O) R 3m 3 2/m

VIII/E.16-70 Petarasite Na5Zr2Si6O18(Cl,OH)·2(H2O) P 2₁/m 2/m

Other Koashvite Information

References:

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

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Koashvite

Na6(Ca,Mn)(Ti,Fe)Si6O18·(H2O)
Dana No: 61.1.2b.2 Strunz No: VIII/E.16-50
Locality:

Notes: