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 % Na₂O

Calcium 13.18 % Ca 18.44 % CaO

Magnesium 5.33 % Mg 8.84 % MgO

Iron 12.24 % Fe 7.88 % FeO / 8.75 % Fe₂O₃

Silicon 24.63 % Si 52.69 % SiO₂

Oxygen 42.09 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ca_0.75Na_0.25Mg_0.5Fe²⁺_0.25Fe³⁺_0.25(Si₂O₆)

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:

Click Here for Larger Aegirine-augite Image

Aegirine-augite Dellaventuraite

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 - PrismaticH-M Symbol (2/m) Space Group: C 2/c

Crystal Structure:

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Bertolo S , Nimis P , Dal Negro A , American Mineralogist , 79 (1994) p.668-674, Low-Ca augite from experimental alkali basalt at 18 kbar: Structural variation, near the miscibility gap, Atomic parameters from ICSD

View Additional jPOWD Structure files for Aegirine-augite
[1]

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:

PE_{Aegirine-augite}= 6.34 barns/electron
U=PE_{Aegirine-augite} x rElectron 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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Print or Cut-and-Paste your Aegirine-augite Specimen Label here :

Aegirine-augite

(Ca,Na)(Mg,Fe++,Fe+++)[Si2O6]
Dana No: 65.01.03b.02 Strunz No: 09.DA.20
Locality:

Notes: