Omphacite Mineral Data

Omphacite Mineral Data +

[Mineral Forums] [Minerals for Sale] [About Us] [En Espanol] [Mineral Gallery]
Fabre Minerals - Europe's first Internet mineral dealer, on the web since 1996

General Omphacite Information

Chemical Formula:

(Ca,Na)(Mg,Fe++,Al)Si2O6

Composition:

Molecular Weight = 211.37 gm

Sodium 3.26 % Na 4.40 % Na₂O

Calcium 11.38 % Ca 15.92 % CaO

Magnesium 6.90 % Mg 11.44 % MgO

Aluminum 3.83 % Al 7.24 % Al₂O₃

Iron 2.64 % Fe 3.40 % FeO

Silicon 26.57 % Si 56.85 % SiO₂

Oxygen 45.42 % O

______ ______

100.00 % 99.24 % = TOTAL OXIDE

Empirical Formula:

Ca_0.6Na_0.3Mg_0.6Al_0.3Fe²⁺_0.1Si₂O₆

Environment:

Major constituent of eclogite, commonly in kimberlite pipes; from some ophiolites and glaucophane-bearing blueschist facies rocks.

IMA Status:

Valid Species (Pre-IMA) 1815

Locality:

Tiburon Pininsula, Marin County, and Sonoma County, California, USA. Link to MinDat.org Location Data.

Name Origin:

From the Greek for "unripe grapes", in allusion to its green color.

Synonym:

ICSD 63236

PDF 42-568

Omphacite Image

Images:

Omphacite

Comments: Dark green crystalline omphacite with glaucophane.
Location: Healdsburg, Sonoma County, California, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Omphacite Crystallography

Axial Ratios:

a:b:c =1.0921:1:0.5993

Cell Dimensions:

a = 9.585, b = 8.776, c = 5.26, Z = 4; beta = 106.85° V = 423.46 Den(Calc)= 3.32

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: P 2/n

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

By Intensity(I/I_o): 2.98(1), 1.4(0.8), 2.13(0.7),

Crystal Structure:

Mouse
drag1 - LMB Manipulate Structure
drag2 - RMB Resize/Rotate
Keyboard
S - Stereo Pair on/off
H - Help Screen
I - Data Info
A - Atoms On/Off
P - Polyhedra On/Off
B - Bonds On/Off
Help on Above

Clark J R , Papike J J , American Mineralogist , 53 (1968) p.840-868, Crystal-chemical characterization of omphacites

View Additional jPOWD Structure files for Omphacite
[1] [2] [3] [4] [5] [6] [7]

Physical Properties of Omphacite

Cleavage:

[110] Good, [110] Good

Color:

Grass green, Dark green.

Density:

3.29 - 3.39, Average = 3.34

Diaphaniety:

Translucent

Fracture:

Brittle - Conchoidal - Very brittle fracture producing small, conchoidal fragments.

Habit:

Anhedral Grains - Granular minerals without the expression of crystal shapes

Habit:

Massive - Granular - Common texture observed in granite and other igneous rock.

Hardness:

5-6 - Between Apatite and Orthoclase

Luster:

Vitreous - Silky

Streak:

greenish white

Optical Properties of Omphacite

Gladstone-Dale:

CI meas= -0.014 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.021 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2085,KPDmeas= 0.2072,KC= 0.2043

Optical Data:

Biaxial (+), a=1.662-1.701, b=1.67-1.712, g=1.685-1.723, bire=0.0220-0.0230, 2V(Calc)=74-88, 2V(Meas)=58-83. Dispersion r > v moderate.

Pleochroism (x):

colorless.

Pleochroism (y):

very pale green.

Pleochroism (z):

very pale greenish blue or very pale green.

Calculated Properties of Omphacite

Electron Density:

r_electron=3.32 gm/cc
note: r_Omphacite=3.34 gm/cc.

Fermion Index

Fermion Index = 0.02024
Boson Index = 0.97976

Photoelectric:

PE_Omphacite= 3.51 barns/electron
U=PE_Omphacite x r_electron= 11.66 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Omphacite is Not Radioactive

Omphacite Classification

Dana Class:

65.1.3b.1 (65)Inosilicate Single-Width Unbranched Chains, W=1

(65.1)with chains P=2

(65.1.3b)C2/c clinopyroxenes (intermediate clinopyroxenes)

65.1.3b.1 Omphacite (Ca,Na)(Mg,Fe,Al)Si2O6 P 2/n 2/m

65.1.3b.2 Aegirine-augite* (Ca,Na)(Mg,Fe,Fe)[Si2O6] C 2/c 2/m

Strunz Class:

VIII/F.01-100 VIII - Silicates

VIII/F - Inosilicates (chain and band) double chains [Si2O6]4-

VIII/F.01 - Pyroxene group, Clinopyroxene

VIII/F.01-10 Clinoenstatite Mg2Si2O6 P 2₁/c 2/m

VIII/F.01-20 Clinoferrosilite (Fe,Mg)2Si2O6 P 2₁/c 2/m

VIII/F.01-30 Kanoite (Mn,Mg)2Si2O6 P 2₁/c 2/m

VIII/F.01-40 Pigeonite (Mg,Fe,Ca)(Mg,Fe)Si2O6 P 2₁/c 2/m

VIII/F.01-50 Diopside CaMgSi2O6 C 2/c 2/m

VIII/F.01-60 Hedenbergite CaFeSi2O6 C 2/c 2/m

VIII/F.01-70 Johannsenite CaMnSi2O6 C 2/c 2/m

VIII/F.01-80 Petedunnite Ca(Zn,Mn,Fe,Mg)Si2O6 C 2/c 2/m

VIII/F.01-90 Augite (Ca,Na)(Mg,Fe,Al,Ti)(Si,Al)2O6 C 2/c 2/m

VIII/F.01-100 Omphacite (Ca,Na)(Mg,Fe,Al)Si2O6 P 2/n 2/m

VIII/F.01-110 Esseneite CaFeAlSiO6 C 2/c 2/m

VIII/F.01-120 Spodumene LiAlSi2O6 C 2/c 2/m

VIII/F.01-130 Jadeite Na(Al,Fe)Si2O6 C 2/c 2/m

VIII/F.01-140 Aegirine NaFeSi2O6 C 2/c 2/m

VIII/F.01-145 Namansilite NaMn(Si2O6) C 2/c 2/m

VIII/F.01-150 Jervisite (Na,Ca,Fe)(Sc,Mg,Fe)Si2O6 C 2/c 2/m

VIII/F.01-160 Natalyite Na(V,Cr)Si2O6 C 2/c 2/m

VIII/F.01-170 Kosmochlor NaCrSi2O6 C 2/c 2/m

Other Omphacite Information

References:

NAME( AntBidBlaNic2) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(AntBidBlaNic2)

See Also:

Links to other databases for Omphacite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - Google Images
6 - Google Scholar
7 - Handbook of Mineralogy (MinSocAm)
8 - Handbook of Mineralogy (UofA)
9 - MinDAT
10 - MinMax(Deutsch)
11 - MinMax(English)
12 - Mineral and Gemstone Kingdom
13 - Mineralienatlas (Deutsch)
14 - QUT Mineral Atlas
15 - Ruff.Info
16 - WWW-MINCRYST

Search for Omphacite using:

[ALTAVISTA] [AOL] [All-The-Web] [HotBot] [Ixquick] [MAMMA] [MSN.COM] [Netscape] [Scirus] [Teoma] [Wikipedia] [YAHOO]

Visit our Advertisers for Omphacite :

AA Mineral Specimens

B & L Fine Minerals

Dan Weinrich Fine Minerals

Dan Weinrich Auctions

John Betts Fine Minerals

Mason's Minerals

Mineral News

Mineral of the Month Club

MineralsWeb Fine Minerals

The GeoZone

Wrights Rock Shop

Translate Omphacite Mineral Data :

Ask about Omphacite here :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
Original Rockhounds Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Mineral Discussion Forum from Fabre Minerals - also available in Español

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

Omphacite

(Ca,Na)(Mg,Fe++,Al)Si2O6
Dana No: 65.1.3b.1 Strunz No: VIII/F.01-100
Locality:

Notes: