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 % Na2 O
Calcium 22.36 % Ca 31.29 % CaO
Magnesium 2.71 % Mg 4.50 % MgO
Aluminum 6.02 % Al 11.38 % Al2 O3
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:
Ca1.5 Na0.5 Al0.6 Mg0.3 Fe2+ 0.1 (Si2 O7 )
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 �kermanite.
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
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 - Scalenohedral H-M Symbol (4 2m) Space Group: P 4 21 m
X Ray Diffraction:
By Intensity(I/Io ): 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:
PEAlumoakermanite = 4.46 barns/electronU=PEAlumoakermanite x r Electron 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 4 21 m 4 2m
55.04.01.02 Gehlenite Ca2Al(AlSi)O7 P 4 21 m 4 2m
55.04.01.03 Melilite (Ca,Na)2(Al,Mg,Fe)(Si,Al)2O7 P 4 21 m 4 2m
55.04.01.04 Okayamalite ! Ca2B2SiO7 P 4 21 m 4 2m
55.04.01.05 Alumoakermanite ! (Ca,Na)2(Al,Mg,Fe)(Si2O7) P 4 21 m 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 4 21 m 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:
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