Andradite Mineral Data

Andradite Mineral Data +

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General Andradite Information

Chemical Formula:

Ca3Fe+++2(SiO4)3

Composition:

Molecular Weight = 508.18 gm

Calcium 23.66 % Ca 33.11 % CaO

Iron 21.98 % Fe 28.28 % FeO

Silicon 16.58 % Si 35.47 % SiO₂

Oxygen 37.78 % O

______ ______

100.00 % 96.85 % = TOTAL OXIDE

Empirical Formula:

Ca₃Fe²⁺₂(SiO₄)₃

Environment:

Igneous and metamorphic rocks.

IMA Status:

Valid Species (Pre-IMA) 1868

Locality:

Magnet Cove, Arkansas. Link to MinDat.org Location Data.

Name Origin:

Andradite is named after the Brazilian mineralogist J. B. de Andrada e Silva (1763-1838). Demantoid is named after its adamantine luster.

Synonym:

Demantoid - green

ICSD 27370

Melanite - black

PDF 10-288

Topazolite - yellow

Andradite Image

Images:

Andradite Clinochlore

Comments: Transparent topazolite, the yellow variety of andradite on clinochlore.
Location: Yellow Cat Mine, New Idria District, San Benito County. California, USA. Scale: 2.7 x 2.5 cm.
© Fabre Minerals

Images:

Andradite

Comments: Andradite (var. Demantoid) Garnet.
Location: Namgar mine, Erongo Mts. Namibia. Scale: 3.5 x 3.2 cm.
© Fabre Minerals

Andradite Crystallography

Cell Dimensions:

a = 12.05, Z = 8; V = 1,749.69 Den(Calc)= 3.86

Crystal System:

Isometric - HexoctahedralH-M Symbol (4/m 3 2/m) Space Group: I a3d

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

By Intensity(I/I_o): 2.696(1), 1.6112(0.6), 3.015(0.6),

Forms:

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Forms: [ 1 1 2]

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Crystal Structure:

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Novak G A , Gibbs G V , American Mineralogist , 56 (1971) p.791-823, The crystal chemistry of the silicate garnets, sample An

View Additional jPOWD Structure files for Andradite
[1] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [2] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [3] [30] [4] [5] [6] [7] [8] [9]

Physical Properties of Andradite

Cleavage:

None

Color:

Black, Yellowish brown, Red, Greenish yellow, Gray.

Density:

3.7 - 4.1, Average = 3.9

Diaphaniety:

Transparent to translucent

Fracture:

Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).

Habit:

Crystalline - Coarse - Occurs as well-formed coarse sized crystals.

Habit:

Euhedral Crystals - Occurs as well-formed crystals showing good external form.

Habit:

Massive - Uniformly indistinguishable crystals forming large masses.

Hardness:

6.5-7 - Pyrite-Quartz

Luminescence:

None.

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Andradite

Gladstone-Dale:

CI meas= -0.149 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= -0.16 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.228,KPDmeas= 0.2256,KC= 0.1965

Optical Data:

Isotropic, n=1.87-1.89.

Calculated Properties of Andradite

Electron Density:

r_electron=3.84 gm/cc
note: r_Andradite=3.90 gm/cc.

Fermion Index

Fermion Index = 0.0129
Boson Index = 0.9871

Photoelectric:

PE_Andradite= 10.08 barns/electron
U=PE_Andradite x r_electron= 38.70 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Andradite is Not Radioactive

Andradite Classification

Dana Class:

51.4.3b.1 (51)Nesosilicate Insular SiO4 Groups Only

(51.4)with cations in [6] and >[6] coordination

(51.4.3b)Garnet group (Ugrandite series)

51.4.3b.1 Andradite Ca3Fe2(SiO4)3 I a3d 4/m 3 2/m

51.4.3b.2 Grossular Ca3Al2(SiO4)3 I a3d 4/m 3 2/m

51.4.3b.3 Uvarovite Ca3Cr2(SiO4)3 I a3d 4/m 3 2/m

51.4.3b.4 Goldmanite Ca3(V,Al,Fe)2(SiO4)3 I a3d 4/m 3 2/m

51.4.3b.5 Yamatoite? (Mn,Ca)3(V,Al)2(SiO4)3 I a3d 4/m 3 2/m

Strunz Class:

VIII/A.08-110 VIII - Silicates

VIII/A - Nesosilicates with [SiO4]4-groups, cations of octahedral and cubic orientation [8+6]

VIII/A.08 - Garnet group, Pyrope - Henritermierite

VIII/A.08-10 Pyrope Mg3Al2(SiO4)3 I a3d 4/m 3 2/m

VIII/A.08-20 Almandine Fe3Al2(SiO4)3 I a3d 4/m 3 2/m

VIII/A.08-30 Spessartine Mn3Al2(SiO4)3 I a3d 4/m 3 2/m

VIII/A.08-40 Calderite (Mn,Ca)3(Fe,Al)2(SiO4)3 I a3d 4/m 3 2/m

VIII/A.08-50 Knorringite Mg3Cr2(SiO4)3 I a3d 4/m 3 2/m

VIII/A.08-60 Majorite Mg3(Fe,Al,Si)2(SiO4)3 I a3d 4/m 3 2/m

VIII/A.08-70 Grossular Ca3Al2(SiO4)3 I a3d 4/m 3 2/m

VIII/A.08-80 Hibschite Ca3Al2(SiO4)3-x(OH)4x(x=0.2-1.5) I a3d 4/m 3 2/m

VIII/A.08-90 Katoite Ca3Al2(SiO4)3-x(OH)4xx=1.5-3 I a3d 4/m 3 2/m

VIII/A.08-100 Hydrougrandite? (Ca,Mg,Fe)3(Fe,Al)2(SiO4)3-x(OH)4x I a3d 4/m 3 2/m

VIII/A.08-110 Andradite Ca3Fe2(SiO4)3 I a3d 4/m 3 2/m

VIII/A.08-120 Schorlomite Ca3(Ti,Fe,Al)2[(Si,Fe,Fe)O4]3 I a3d 4/m 3 2/m

VIII/A.08-125 Morimotoite Ca3TiFeSi3O12 I a3d 4/m 3 2/m

VIII/A.08-130 Uvarovite Ca3Cr2(SiO4)3 I a3d 4/m 3 2/m

VIII/A.08-138 Yamatoite! (Mn,Ca)3(V,Al)2(SiO4)3 I a3d 4/m 3 2/m

VIII/A.08-140 Goldmanite Ca3(V,Al,Fe)2(SiO4)3 I a3d 4/m 3 2/m

VIII/A.08-150 Kimzeyite Ca3(Zr,Ti)2(Si,Al,Fe)3O12 I a3d 4/m 3 2/m

VIII/A.08-160 Henritermierite Ca3(Mn,Al)2(SiO4)2(OH)4 I 4₁/acd 4/m 2/m 2/m

Other Andradite Information

References:

NAME( ODonoghue90) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Mason68)

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Andradite

Ca3Fe+++2(SiO4)3
Dana No: 51.4.3b.1 Strunz No: VIII/A.08-110
Locality:

Notes: