Jeffreyite Mineral Data

Jeffreyite Mineral Data +

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General Jeffreyite Information

Chemical Formula:

(Ca,Na)2(Be,Al)Si2(O,OH)7

Composition:

Molecular Weight = 255.30 gm

Sodium 4.50 % Na 6.07 % Na₂O

Calcium 23.55 % Ca 32.95 % CaO

Beryllium 2.65 % Be 7.35 % BeO

Aluminum 2.64 % Al 4.99 % Al₂O₃

Silicon 22.00 % Si 47.07 % SiO₂

Hydrogen 0.79 % H 7.06 % H₂O

Oxygen 43.87 % O

______ ______

100.00 % 105.48 % = TOTAL OXIDE

Empirical Formula:

Ca_1.5Na_0.5Be_0.75Al_0.25Si₂O₅(OH)₂

IMA Status:

Approved IMA 1984

Locality:

Link to MinDat.org Location Data.

Synonym:

IMA1982-075

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Jeffreyite Crystallography

Axial Ratios:

a:b:c =1:1:2.712

Cell Dimensions:

a = 14.9, b = 14.9, c = 40.41, Z = 64; V = 8,971.42 Den(Calc)= 3.02

Crystal System:

Orthorhombic - DisphenoidalH-M Symbol (2 2 2) Space Group: C 222₁

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

By Intensity(I/I_o): 2.774(1), 2.993(0.9), 2.541(0.7),

Physical Properties of Jeffreyite

Cleavage:

[001] Perfect, [110] Perfect

Color:

Colorless.

Density:

2.99

Diaphaniety:

Transparent

Fracture:

Brittle - Generally displayed by glasses and most non-metallic minerals.

Hardness:

5 - Apatite

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Jeffreyite

Gladstone-Dale:

CI meas= 0.077 (Fair) - where the CI = (1-KPDmeas/KC)
CI calc= 0.086 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2107,KPDmeas= 0.2128,KC= 0.2306

Optical Data:

Biaxial (-), a=1.625, b=1.641, g=1.643, bire=0.0180, 2V(Calc)=38, 2V(Meas)=40.

Calculated Properties of Jeffreyite

Electron Density:

r_electron=2.99 gm/cc
note: r_Jeffreyite=2.99 gm/cc.

Fermion Index

Fermion Index = 0.03727
Boson Index = 0.96273

Photoelectric:

PE_Jeffreyite= 3.89 barns/electron
U=PE_Jeffreyite x r_electron= 11.64 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Jeffreyite is Not Radioactive

Jeffreyite Classification

Dana Class:

55.4.2.3 (55)Sorosilicate Si2O7 Groups, Generally with No Additional Anions

(55.4)with cations in [8] and lower coordination

(55.4.2)Fresnoite group

55.4.2.1 Fresnoite Ba2TiSi2O8 P 4bm 4mm

55.4.2.2 Hardystonite Ca2ZnSi2O7 P 42₁m 4 2m

55.4.2.3 Jeffreyite (Ca,Na)2(Be,Al)Si2(O,OH)7 C 222₁ 2 2 2

55.4.2.4 Leucophanite (Na,Ca)2BeSi2(O,OH,F)7 P1 1

55.4.2.5 Meliphanite (Ca,Na)2Be[(Si,Al)2O6(F,OH)] I 4 4

55.4.2.6 Gugiaite Ca2BeSi2O7 P 42₁m 4 2m

Strunz Class:

VIII/C.02-60 VIII - Silicates

VIII/C - Sorosilicates, with [Si2O7]6-, without anions unfamiliar to tetraheders

VIII/C.02 - Melilite group

VIII/C.02-10 Akermanite Ca2MgSi2O7 P 42₁m 4 2m

VIII/C.02-14 Okayamalite! Ca2B2SiO7 P 42₁m 4 2m

VIII/C.02-15 Gehlenite Ca2Al(AlSi)O7 P 42₁m 4 2m

VIII/C.02-30 Gugiaite Ca2BeSi2O7 P 42₁m 4 2m

VIII/C.02-40 Hardystonite Ca2ZnSi2O7 P 42₁m 4 2m

VIII/C.02-50 Leucophanite (Na,Ca)2BeSi2(O,OH,F)7 P1 1

VIII/C.02-60 Jeffreyite (Ca,Na)2(Be,Al)Si2(O,OH)7 C 222₁ 2 2 2

VIII/C.02-70 Meliphanite (Ca,Na)2Be[(Si,Al)2O6(F,OH)] I 4 4

VIII/C.02-80 Barylite BaBe2Si2O7 Pn21a mm2

VIII/C.02-85 Clinobarylite! BaBe2Si2O7 Pmn2 2/m 2/m 2/m

VIII/C.02-90 Andremeyerite BaFe(Fe,Mn,Mg)Si2O7 P 2₁/c 2/m

Other Jeffreyite Information

References:

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

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

Jeffreyite

(Ca,Na)2(Be,Al)Si2(O,OH)7
Dana No: 55.4.2.3 Strunz No: VIII/C.02-60
Locality:

Notes: