Aenigmatite Mineral Data

General Aenigmatite Information

Chemical Formula:

(Na,Ca)4(Fe++,Ti,Mg)12Si12O40

Composition:

Molecular Weight = 1,717.59 gm

Sodium 4.99 % Na 6.73 % Na₂O

Calcium 0.77 % Ca 1.08 % CaO

Magnesium 0.65 % Mg 1.08 % MgO

Zirconium 0.05 % Zr 0.07 % ZrO₂

Titanium 5.85 % Ti 9.77 % TiO₂

Manganese 1.28 % Mn 1.65 % MnO

Aluminum 1.01 % Al 1.90 % Al₂O₃

Zinc 0.04 % Zn 0.05 % ZnO

Iron 29.95 % Fe 35.76 % FeO / 3.07 % Fe₂O₃

Silicon 18.15 % Si 38.83 % SiO₂

Oxygen 37.26 % O

______ ______

100.00 % 99.99 % = TOTAL OXIDE

Empirical Formula:

Na_3.73Ca_0.27Fe²⁺_8.55Ti_2.1Mg_0.46Fe³⁺_0.4Mn²⁺_0.4Ca_0.06Zn_0.01Zr_0.01Si_11.1Al_0.64Fe³⁺_0.26O₄₀

Environment:

A primary constituent in sodium-rich alkalic volcanics, pegmatites, and other silica-poor igneous rocks.

IMA Status:

Valid Species (Pre-IMA) 1865

Locality:

Notable studied occurrences include: at Naujakasik, near the Tunugdliarfik Fjord, and on the Kangerdluarssuk Plateau, in the Ilimaussaq intrusion; from Narssarssuk; and elsewhere in Gr Link to MinDat.org Location Data.

Name Origin:

From the Greek for riddle, apparently an allusion to its (formerly) uncertain chemical composition.

Name Pronunciation:

Aenigmatite + Pronunciation

Synonym:

Cossyrite

ICSD 15283

PDF 46-1473

Aenigmatite Image

Images:

Aenigmatite

Comments: Dark, crystal prism of aenigmatite in white albite with astrophyllite.
Location: Mount Eveslogchorr, Khibiny Massif, Kola Peninsula, Murmansk District, Russia. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Aenigmatite Crystallography

Axial Ratios:

a:b:c =0.9607:1:0.8238

Cell Dimensions:

a = 10.415, b = 10.84, c = 8.931, Z = 1; alpha = 105.107°, beta = 96.61°, gamma = 125.398° V = 788.23 Den(Calc)= 3.62

Crystal System:

Triclinic - Pinacoidal H-M Symbol ( 1) Space Group: P1

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

By Intensity(I/I_o): 3.14(1), 8.11(1), 2.705(0.8),

Physical Properties of Aenigmatite

Cleavage:

{???} Perfect

Color:

Brown, Black.

Density:

3.74 - 3.85, Average = 3.79

Diaphaneity:

Opaque

Habit:

Lamellar - Thin laminae producing a lamellar structure.

Hardness:

5-6 - Between Apatite and Orthoclase

Luminescence:

Non-fluorescent.

Luster:

Subadamantine

Streak:

reddish brown

Optical Properties of Aenigmatite

Gladstone-Dale:

CI meas= 0.011 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.017 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2168,KPDmeas= 0.2183,KC= 0.2207
Ncalc = 1.83 - 1.85

Optical Data:

Biaxial (+), a=1.78-1.8, b=1.8-1.82, g=1.87-1.9, bire=0.0900-0.1000, 2V(Calc)=56-60, 2V(Meas)=27-55. Dispersion single.

Pleochroism (x):

light brown.

Pleochroism (y):

brown.

Pleochroism (z):

dark brown.

Calculated Properties of Aenigmatite

Electron Density:

Bulk Density (Electron Density)=3.68 gm/cc
note: Specific Gravity of Aenigmatite =3.80 gm/cc.

Fermion Index:

Fermion Index = 0.02
Boson Index = 0.98

Photoelectric:

PE_Aenigmatite= 11.27 barns/electron
U=PE_Aenigmatite x rElectron Density= 41.50 barns/cc.

Radioactivity:

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

Aenigmatite Classification

Dana Class:

69.02.01a.01 (69)Inosilicate Chains with Side Branches or Loops

(69.02)with P>2

(69.02.01a)Aenigmatite and related species (Aenigmatite subgroup)

69.02.01a.01 Aenigmatite (Na,Ca)4(Fe,Ti,Mg)12Si12O40 P1 1

69.02.01a.02 Dorrite Ca2Mg2Fe4(Al,Fe)4Si2O20 P1,P 1 Tri

69.02.01a.03 Hogtuvaite (Ca,Na)2(Fe,Fe,Ti,Mg,Mn)6(Si,Be,Al)6O20 P1 1

69.02.01a.04 Krinovite NaMg2CrSi3O10 P1 1

69.02.01a.05 Rhonite Ca2(Mg,Fe,Fe,Ti)6(Si,Al)6O20 P1 1

69.02.01a.06 Serendibite Ca2(Mg,Al)6(Si,Al,B)6O20 P1 1

69.02.01a.07 Welshite Ca4Mg9Sb3O4[Si6Be3AlFe2O36] P1 1

69.02.01a.08 Wilkinsonite Na2Fe4Fe2Si6O20 P1 1

69.02.01a.09 Makarochkinite! Ca2Fe4FeTiSi4BeAlO20 P1 1

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 Aenigmatite Information

References:

NAME( AntBidBlaNic2) PHYS. PROP.(Dana8, AmMin v94:650) OPTIC PROP.(Ford32)

See Also:

Links to other databases for Aenigmatite :
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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Aenigmatite

(Na,Ca)4(Fe++,Ti,Mg)12Si12O40
Dana No: 69.02.01a.01 Strunz No: 09.DH.45
Locality:

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