Alumoakermanite Mineral Data

General Alumoakermanite Information

Chemical Formula:

(Ca,Na)2(Al,Mg,Fe++)(Si2O7)

Composition:

Molecular Weight = 268.84 gm

Sodium 4.28 % Na 5.76 % Na₂O

Calcium 22.36 % Ca 31.29 % CaO

Magnesium 2.71 % Mg 4.50 % MgO

Aluminum 6.02 % Al 11.38 % Al₂O₃

Iron 2.08 % Fe 2.67 % FeO

Silicon 20.89 % Si 44.70 % SiO₂

Oxygen 41.66 % O

______ ______

100.00 % 100.30 % = TOTAL OXIDE

Empirical Formula:

Ca_1.5Na_0.5Al_0.6Mg_0.3Fe²⁺_0.1(Si₂O₇)

Environment:

Found in evolved olivine free melilite-nephelinitic ashes and lapilli-tuffs as a silicate phase in non-carbonatite lavas. Melilite group. Al-dominant analogue of åkermanite.

IMA Status:

Proposed IMA 2008 (Dana # Added)

Locality:

Oldoinyo Lengai volcano, Tanzania Link to MinDat.org Location Data.

Name Origin:

Named as the Al analog of akermanite.

Synonym:

IMA2008-049

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Alumoakermanite Crystallography

Axial Ratios:

a:c = 1:0.64764

Cell Dimensions:

a = 7.7661, c = 5.0297, Z = 2; V = 303.35 Den(Calc)= 2.94

Crystal System:

Tetragonal - ScalenohedralH-M Symbol (4 2m) Space Group: P 42₁m

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

By Intensity(I/I_o): 2.859(1), 2.456(0.32), 3.075(0.25),1.757(0.19), 1.386(0.13), 1.736(0.13), 3.712(0.13), 1.83(0.12),

Physical Properties of Alumoakermanite

Habit:

Tabular - Form dimensions are thin in one direction.

Hardness:

4-5 - Fluorite-Apatite

Optical Properties of Alumoakermanite

Gladstone-Dale:

CI calc= -0.034 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2143,KC= 0.2072
Ncalc = 1.61

Optical Data:

Uniaxial (-), e=1.624-1.626, w=1.635, bire=0.0090-0.0110.

Calculated Properties of Alumoakermanite

Electron Density:

Bulk Density (Electron Density)=2.92 gm/cc
note: Specific Gravity of Alumoakermanite =2.94 gm/cc.

Fermion Index:

Fermion Index = 0.01
Boson Index = 0.99

Photoelectric:

PE_{Alumoakermanite}= 4.46 barns/electron
U=PE_{Alumoakermanite} x rElectron Density= 13.03 barns/cc.

Radioactivity:

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

Alumoakermanite Classification

Dana Class:

55.04.01.05 (55)Sorosilicate Si2O7 Groups, Generally with No Additional Anions

(55.04)with cations in [8] and lower coordination

(55.04.01)Melilite group

55.04.01.01 Akermanite Ca2MgSi2O7 P 42₁m 4 2m

55.04.01.02 Gehlenite Ca2Al(AlSi)O7 P 42₁m 4 2m

55.04.01.03 Melilite (Ca,Na)2(Al,Mg,Fe)(Si,Al)2O7 P 42₁m 4 2m

55.04.01.04 Okayamalite! Ca2B2SiO7 P 42₁m 4 2m

55.04.01.05 Alumoakermanite! (Ca,Na)2(Al,Mg,Fe)(Si2O7) P 42₁m 4 2m

Strunz Class:

08.DE.35 08 - PHOSPHATES, ARSENATES, VANADATES

08.D - Phosphates, etc

08.DE -With only medium-sized cations, (OH, etc.):RO4 = 3:1

08.DE.35 Aldermanite Mg5Al12(PO4)8(OH)22•32(H2O) Unk Ortho

08.DE.35 Alumoakermanite! (Ca,Na)2(Al,Mg,Fe)(Si2O7) P 42₁m 4 2m

Other Alumoakermanite Information

See Also:

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

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

Alumoakermanite

(Ca,Na)2(Al,Mg,Fe++)(Si2O7)
Dana No: 55.04.01.05 Strunz No: 08.DE.35
Locality:

Notes: