Pyrope Mineral Data

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General Pyrope Information

Chemical Formula:

Mg3Al2(SiO4)3

Composition:

Molecular Weight = 403.13 gm

Magnesium 18.09 % Mg 29.99 % MgO

Aluminum 13.39 % Al 25.29 % Al₂O₃

Silicon 20.90 % Si 44.71 % SiO₂

Oxygen 47.63 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Mg₃Al₂(SiO₄)₃

Environment:

Ultra basic igneous rocks.

IMA Status:

Valid Species (Pre-IMA) 1803

Locality:

Zoblitz, Germany. Link to MinDat.org Location Data.

Name Origin:

From the Greek, pyropos, "fiery-eyed" in allusion to the red hue.

Synonym:

ICSD 71887

PDF 15-742

Rhodolite

Pyrope Image

Images:

Pyrope

Comments: Transparent, dark-red pyrope garnet.
Location: Governador Valadares, Rio Doce, Minas Gerais, Southeast Region, Brazil. Scale: 6x6x6 mm.
© John Betts - Fine Minerals

Pyrope Crystallography

Cell Dimensions:

a = 11.459, Z = 8; V = 1,504.67 Den(Calc)= 3.56

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): 1.54(1), 2.58(1), 2.88(0.6),

Forms:

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Forms: [ 2 1 1]

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Crystal Structure:

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Gibbs G V , Smith J V , American Mineralogist , 50 (1965) p.2023-2039, Refinement of the crystal structure of synthetic pyrope, refinement D, note that temperature factors reported for Si were labelled, incorrectly in the paper

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

Physical Properties of Pyrope

Cleavage:

None

Color:

Blood red, Orange red, Purple red, Pink, Black red.

Density:

3.65 - 3.84, Average = 3.74

Diaphaniety:

Transparent to subtranslucent

Fracture:

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

Habit:

Crystalline - Fine - Occurs as well-formed fine sized crystals.

Habit:

Granular - Generally occurs as anhedral to subhedral crystals in matrix.

Habit:

Lamellar - Thin laminae producing a lamellar structure.

Hardness:

7.5 - Garnet

Luminescence:

None.

Luster:

Vitreous (Glassy)

Magnetism:

Nonmagnetic

Streak:

white

Optical Properties of Pyrope

Gladstone-Dale:

CI meas= 0.031 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= -0.019 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2093,KPDmeas= 0.1989,KC= 0.2053

Optical Data:

Isotropic, n=1.73-1.76.

Calculated Properties of Pyrope

Electron Density:

r_electron=3.53 gm/cc
note: r_Pyrope=3.56 gm/cc.

Fermion Index

Fermion Index = 0.02807
Boson Index = 0.97193

Photoelectric:

PE_Pyrope= 1.59 barns/electron
U=PE_Pyrope x r_electron= 5.63 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Pyrope is Not Radioactive

Pyrope Classification

Dana Class:

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

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

(51.4.3a)Garnet group (Pyralspite series)

51.4.3a.1 Pyrope Mg3Al2(SiO4)3 I a3d 4/m 3 2/m

51.4.3a.2 Almandine Fe3Al2(SiO4)3 I a3d 4/m 3 2/m

51.4.3a.3 Spessartine Mn3Al2(SiO4)3 I a3d 4/m 3 2/m

51.4.3a.4 Knorringite Mg3Cr2(SiO4)3 I a3d 4/m 3 2/m

51.4.3a.5 Majorite Mg3(Fe,Al,Si)2(SiO4)3 I a3d 4/m 3 2/m

51.4.3a.6 Calderite (Mn,Ca)3(Fe,Al)2(SiO4)3 I a3d 4/m 3 2/m

Strunz Class:

VIII/A.08-10 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 Pyrope Information

References:

NAME( Sinkankas66) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Sinkankas66)

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

Pyrope

Mg3Al2(SiO4)3
Dana No: 51.4.3a.1 Strunz No: VIII/A.08-10
Locality:

Notes: