Megacyclite Mineral Data

General Megacyclite Information

Chemical Formula:

Na8KSi9O18(OH)9•19(H2O)

Composition:

Molecular Weight = 1,250.12 gm

Potassium 3.13 % K 3.77 % K₂O

Sodium 14.71 % Na 19.83 % Na₂O

Silicon 20.22 % Si 43.26 % SiO₂

Hydrogen 3.71 % H 33.14 % H₂O

Oxygen 58.23 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Na₈KSi₉O₁₈(OH)₉•18.5(H₂O)

Environment:

In unweathered ultra-alkalic pegmatites in an alkalic massif. Turns white on exposure to air.

IMA Status:

Approved IMA 1993

Locality:

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

Name Origin:

From the Greek for large and cyclical, with reference to the large ringlike groups of silica tetrahedra in the structure.

Name Pronunciation:

Megacyclite + Pronunciation

Synonym:

IMA1991-015

Megacyclite Crystallography

Axial Ratios:

a:b:c =2.0862:1:1.2495

Cell Dimensions:

a = 24.91, b = 11.94, c = 14.92, Z = 4; beta = 94.47° V = 4,424.09 Den(Calc)= 1.88

Crystal System:

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

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

By Intensity(I/I_o): 3.08(1), 2.938(0.7), 2.64(0.6),4.26(0.6), 2.289(0.35), 2.4(0.35), 7.42(0.2),

Physical Properties of Megacyclite

Cleavage:

{100} Perfect, {001} Good

Color:

Colorless, White.

Density:

1.82

Diaphaneity:

Transparent

Fracture:

Regular - Flat surfaces (not cleavage) fractured in a regular pattern.

Habit:

Irregular Grains - Occurs as splotchy, anhedral crystals forming inclusions in other minerals or rocks.

Hardness:

2 - Gypsum

Luster:

Vitreous - Dull

Streak:

white

Optical Properties of Megacyclite

Gladstone-Dale:

CI meas= -0.049 (Good) - where the CI = (1-KPDmeas/KC)
CI calc= -0.016 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2516,KPDmeas= 0.2599,KC= 0.2477
Ncalc = 1.45 - 1.47

Optical Data:

Biaxial (-), a=1.46, b=1.478, g=1.481, bire=0.0210, 2V(Calc)=44, 2V(Meas)=44. Dispersion r > v strong.

Calculated Properties of Megacyclite

Electron Density:

Bulk Density (Electron Density)=1.93 gm/cc
note: Specific Gravity of Megacyclite =1.88 gm/cc.

Fermion Index:

Fermion Index = 0.0097313629
Boson Index = 0.9902686371

Photoelectric:

PE_Megacyclite= 1.40 barns/electron
U=PE_Megacyclite x r_electron= 2.70 barns/cc.

Radioactivity:

GRapi = 46.44 (Gamma Ray American Petroleum Institute Units)
Concentration of Megacyclite per GRapi unit = 2.15 (%)

Estimated Radioactivity from Megacyclite - barely detectable

Megacyclite Classification

Dana Class:

62.01.02.01 (62)Cyclosilicate Eight-Membered Rings

(62.01)with 8-memebered and larger rings

(62.01.02)Dana Group

62.01.02.01 Megacyclite Na8KSi9O18(OH)9•19(H2O) P 2₁/c 2/m

Strunz Class:

09.CP.10 09 - SILICATES (Germanates)

09.C - Cyclosilicates

09.CP -12-membered and larger rings

09.CP.10 Megacyclite Na8KSi9O18(OH)9•19(H2O) P 2₁/c 2/m

Other Megacyclite Information

References:

NAME( AntBidBlaNic2) PHYS. PROP.(AntBidBlaNic2) OPTIC PROP.(AntBidBlaNic2)

See Also:

Links to other databases for Megacyclite :
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
15 - WWW-MINCRYST

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

Megacyclite

Na8KSi9O18(OH)9•19(H2O)
Dana No: 62.01.02.01 Strunz No: 09.CP.10
Locality:

Notes:

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