Khmaralite Mineral Data

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General Khmaralite Information

Chemical Formula:

(Mg,Al,Fe)16(Al,Si,Be)12O40

Composition:

Molecular Weight = 1,401.96 gm

Magnesium 16.64 % Mg 27.60 % MgO

Beryllium 1.03 % Be 2.85 % BeO

Aluminum 23.09 % Al 43.64 % Al₂O₃

Iron 6.37 % Fe 8.20 % FeO

Silicon 7.21 % Si 15.43 % SiO₂

Oxygen 45.65 % O

______ ______

100.00 % 97.72 % = TOTAL OXIDE

Empirical Formula:

Mg_9.6Al_4.8Fe²⁺_1.6Al_7.2Si_3.6Be_1.6O₄₀

Environment:

In a single specimen of a pegmatite. A member of the sapphirine group

IMA Status:

Approved IMA 1998 (Dana # Added)

Locality:

From "Zircon Point,", Khmara Bay, Enderby Land, Antarctica. Link to MinDat.org Location Data.

Name Origin:

For the locality, which was named in honor of Ivan Fedorovich Khmara (1936-1956), a tractor driver who perished in Antarctica.

Synonym:

ICSD 87692

IMA1998-027

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Khmaralite Crystallography

Axial Ratios:

a:b:c =1.3081:1:0.7831

Cell Dimensions:

a = 18.8, b = 14.371, c = 11.254, Z = 4; beta = 125.53° V = 2,474.43 Den(Calc)= 3.76

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: P 2₁/c

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

By Intensity(I/I_o): 2.4446(1), 2.0106(0.85), 2.01(0.61),2.826(0.45), 2.4385(0.44), 2.3405(0.43),

Crystal Structure:

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Barbier J , Grew E S , Moore P B , Su S-C , American Mineralogist , 84 (1999) p.1650-1660, Khmaralite, a new beryllium-bearing mineral related to sapphirine:, A superstructure resulting from partial ordering of Be, Al and Si on, tetrahedral sites

Physical Properties of Khmaralite

Cleavage:

None

Color:

Very dark green.

Diaphaneity:

Transparent

Fracture:

Brittle - Uneven - Very brittle fracture producing uneven fragments.

Habit:

Aggregates - Made of numerous individual crystals or clusters.

Habit:

Foliated - Two dimensional platy forms.

Habit:

Tabular - Form dimensions are thin in one direction.

Hardness:

7 - Quartz

Luster:

Vitreous (Glassy)

Streak:

grayish green

Optical Properties of Khmaralite

Gladstone-Dale:

CI calc= 0.022 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1956,KC= 0.1999
Ncalc = 1.75

Optical Data:

Biaxial (-), a=1.725, b=1.74, g=1.741, bire=0.0160, 2V(Calc)=28, 2V(Meas)=34. Dispersion r > v strong.

Calculated Properties of Khmaralite

Electron Density:

Bulk Density (Electron Density)=3.70 gm/cc
note: Specific Gravity of Khmaralite =3.76 gm/cc.

Fermion Index:

Fermion Index = 0.03
Boson Index = 0.97

Photoelectric:

PE_Khmaralite= 3.22 barns/electron
U=PE_Khmaralite x rElectron Density= 11.92 barns/cc.

Radioactivity:

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

Khmaralite Classification

Dana Class:

69.02.01b.03 (69)Inosilicate Chains with Side Branches or Loops

(69.02)with P>2

(69.02.01b)Aenigmatite and related species (Sapphirine subgroup)

69.02.01b.01 Sapphirine (Mg,Al)8(Al,Si)6O20 P1 1

69.02.01b.02 Surinamite (Mg,Fe)3Al4BeSi3O16 P 2₁/n 2/m

69.02.01b.03 Khmaralite! (Mg,Al,Fe)16(Al,Si,Be)12O40 P 2₁/c 2/m

Strunz Class:

09.DH.45 09 - SILICATES (Germanates)

09.D - Inosilicates* Structural terminology according to Liebau (1985)

09.DH -Inosilicates with 4-periodic single chains, Si4O12

09.DH.45 Aenigmatite (Na,Ca)4(Fe,Ti,Mg)12Si12O40 P1 1

09.DH.45 Dorrite Ca2Mg2Fe4(Al,Fe)4Si2O20 P1,P 1 Tri

09.DH.45 Krinovite NaMg2CrSi3O10 P1 1

09.DH.45 Rhonite Ca2(Mg,Fe,Fe,Ti)6(Si,Al)6O20 P1 1

09.DH.45 Sapphirine (Mg,Al)8(Al,Si)6O20 P1 1

09.DH.45 Serendibite Ca2(Mg,Al)6(Si,Al,B)6O20 P1 1

09.DH.45 Khmaralite! (Mg,Al,Fe)16(Al,Si,Be)12O40 P 2₁/c 2/m

09.DH.45 Makarochkinite! Ca2Fe4FeTiSi4BeAlO20 P1 1

09.DH.45 Welshite Ca4Mg9Sb3O4[Si6Be3AlFe2O36] P1 1

09.DH.45 Wilkinsonite Na2Fe4Fe2Si6O20 P1 1

Other Khmaralite Information

References:

NAME( MinRec, Vol 31, No 4) PHYS. PROP.(MinRec, Vol 31, No 4) OPTIC PROP.(MinRec, Vol 31, No 4)

See Also:

Links to other databases for Khmaralite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - Google Images
4 - Google Scholar
5 - MinDAT
6 - MinMax(Deutsch)
7 - MinMax(English)
8 - Mineralienatlas (Deutsch)
9 - QUT Mineral Atlas
10 - Ruff.Info

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Khmaralite

(Mg,Al,Fe)16(Al,Si,Be)12O40
Dana No: 69.02.01b.03 Strunz No: 09.DH.45
Locality:

Notes: