Aegirine-augite Mineral Data
General Aegirine-augite Information
Chemical Formula:
(Ca,Na)(Mg,Fe++,Fe+++)[Si2O6]
Composition:
Molecular Weight = 228.05 gm
Sodium 2.52 % Na 3.40 % Na2 O
Calcium 13.18 % Ca 18.44 % CaO
Magnesium 5.33 % Mg 8.84 % MgO
Iron 12.24 % Fe 7.88 % FeO / 8.75 % Fe2 O3
Silicon 24.63 % Si 52.69 % SiO2
Oxygen 42.09 % O
______ ______
100.00 % 100.00 % = TOTAL OXIDE
Empirical Formula:
Ca0.75 Na0.25 Mg0.5 Fe2+ 0.25 Fe3+ 0.25 (Si2 O6 )
Environment:
Characteristic mineral of alkaline rocks, particularly syenites and iron-rich metamorphic and metasomatic rocks.
IMA Status:
Not Approved IMA 1950
Locality:
Common world-wide. Link to MinDat.org Location Data.
Name Origin:
Name derived from its intermediate pyroxene composition. This is not an end-member species.
Name Pronunciation:
Aegirine-augite
Aegirine-augite Image
Images:
Dellaventuraite Aegirine-augite
Comments: View in plane-polarized light of reddish brown dellaventuraite (OPTK) as an overgrowth on purple-gray aegirine-augite (AE-AG) in a matrix of rounded quartz (QZ) with minor rounded (high relief) apatite grains. (AmMin 90:306).
Location: Kajlidongri manganese mine, Jhabua District, Madhya Pradesh, India.
Scale: Picture size 2.5 cm.
© American Mineralogist
Aegirine-augite Crystallography
Axial Ratios:
a:b:c =1.1012:1:0.5984
Cell Dimensions:
a = 9.68, b = 8.79, c = 5.26, Z = 4; beta = 105° V = 432.31 Den(Calc)= 3.50
Crystal System:
Monoclinic - Prismatic H-M Symbol (2/m) Space Group: C 2/c
Physical Properties of Aegirine-augite
Cleavage:
{110} Very Good, {100} Parting
Color:
Dark green, Black, Green, Pale greenish yellow, Greenish gray.
Density:
3.4 - 3.6, Average = 3.5
Diaphaneity:
Translucent to opaque
Fracture:
Brittle - Splintery - Brittle fracture leaving splintery fragments.
Habit:
Anhedral Grains - Granular minerals without the expression of crystal shapes
Habit:
Fibrous - Crystals made up of fibers.
Habit:
Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).
Hardness:
6 - Orthoclase
Luster:
Vitreous (Glassy)
Optical Properties of Aegirine-augite
Gladstone-Dale:
CI meas = 0 (Superior) - where the CI = (1-KPDmeas /KC ) CI calc = 0 (Superior) - where the CI = (1-KPDcalc /KC )
KPDcalc = 0.2149,KPDmeas = 0.2149,KC = 0.2148 Ncalc = 1.73 - 1.77
Optical Data:
Biaxial (-), a=1.7-1.76, b=1.71-1.8, g=1.73-1.813, bire=0.0300-0.0530, 2V(Calc)=58-72, 2V(Meas)=70-110. Dispersion r > v moderate.
Calculated Properties of Aegirine-augite
Electron Density:
Bulk Density (Electron Density)=3.46 gm/cc note: Specific Gravity of Aegirine-augite =3.50 gm/cc.
Fermion Index:
Fermion Index = 0.01 Boson Index = 0.99
Photoelectric:
PEAegirine-augite = 6.34 barns/electronU=PEAegirine-augite x r Electron Density= 21.94 barns/cc.
Radioactivity:
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Aegirine-augite is Not Radioactive
Aegirine-augite Classification
Dana Class:
65.01.03b.02 (65) Inosilicate Single-Width Unbranched Chains, W=1
(65.01) with chains P=2
(65.01.03b) C2/c clinopyroxenes (intermediate clinopyroxenes)
65.01.03b.01 Omphacite (Ca,Na)(Mg,Fe,Al)Si2O6 P 2/n 2/m
65.01.03b.02 Aegirine-augite * (Ca,Na)(Mg,Fe,Fe)[Si2O6] C 2/c 2/m
Strunz Class:
09.DA.20 09 - SILICATES (Germanates)
09.D - Inosilicates* Structural terminology according to Liebau (1985)
09.DA -Inosilicates with 2-periodic single chains, Si2O6; pyroxene family
09.DA.20 Aegirine-augite * (Ca,Na)(Mg,Fe,Fe)[Si2O6] C 2/c 2/m
09.DA.20 Omphacite (Ca,Na)(Mg,Fe,Al)Si2O6 P 2/n 2/m
Other Aegirine-augite Information
References:
NAME( Dana8) PHYS. PROP.(Dana8) OPTIC PROP.(Dana8)
See Also:
Links to other databases for Aegirine-augite :
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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Aegirine-augite
(Ca,Na)(Mg,Fe++,Fe+++)[Si2O6]
Dana No: 65.01.03b.02 Strunz No: 09.DA.20
Locality:
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