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

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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 - PinacoidalH-M Symbol ( 1) Space Group: P1 X Ray Diffraction: By Intensity(I/I_o): 3.14(1), 8.11(1), 2.705(0.8), Crystal Structure:

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Cannillo E , Mazzi F , Fang J H , Robinson P D , Ohya Y , American Mineralogist , 56 (1971) p.427-446, The crystal structure of aenigmatite, sample CM View Additional jPOWD Structure files for Aenigmatite [1] [2] [3]

 

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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