Cafetite Mineral Data

Cafetite Mineral Data +

General Cafetite Information

Chemical Formula:

Ca(Fe,Al)2Ti4O12·4(H2O)

Composition:

Molecular Weight = 592.91 gm

Calcium 6.76 % Ca 9.46 % CaO

Titanium 32.30 % Ti 53.89 % TiO₂

Aluminum 2.28 % Al 4.30 % Al₂O₃

Iron 14.13 % Fe 18.18 % FeO

Hydrogen 1.36 % H 12.15 % H₂O

Oxygen 43.18 % O

______ ______

100.00 % 97.98 % = TOTAL OXIDE

Empirical Formula:

CaFe²⁺_1.5Al_0.5Ti₄O₁₂·4(H₂O)

Environment:

In miarolitic cavities in pegmatites cutting pyroxenite. Later work suggests that Fe was a contaminent from magnetite and not an essential part of the formula.

IMA Status:

Approved IMA 1959

Locality:

Afrikanda massif, Kola Peninsula, Russia. Link to MinDat.org Location Data.

Name Origin:

Named for the composition (Ca, Fe, Ti).

Cafetite Image

Images:

Cafetite

Comments: Ocher-colored aggregates of cafetite in pegmatite, intimately mixed with iron hydroxides.
Location: Mount Rasvumchorr, Khibiny Massif, Kola Peninsula, Murmansk District, Russia. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Cafetite Crystallography

Axial Ratios:

a:b:c =0.4084:1:1.3139

Cell Dimensions:

a = 4.9463, b = 12.109, c = 15.911, Z = 3; beta = 98.937° V = 941.42 Den(Calc)= 3.14

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: P 2₁/n

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

By Intensity(I/I_o): 7.86(1), 2.56(0.8), 1.91(0.7),

Crystal Structure:

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Krivovichev S V , Yakovenchuk V N , Burns P C , Pakhomovsky Y A , Menshikov Y P , American Mineralogist , 88 (2003) p.424-429, Cafetite, Ca[Ti2O5](H2O): Crystal structure and revision of chemical formula

Physical Properties of Cafetite

Cleavage:

[???] Good

Color:

Colorless, Pale yellow.

Density:

3.28

Diaphaniety:

Transparent

Fracture:

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

Habit:

Acicular - Occurs as needle-like crystals.

Habit:

Aggregates - Made of numerous individual crystals or clusters.

Habit:

Radial - Crystals radiate from a center without producing stellar forms (e.g. stibnite)

Hardness:

4-5 - Fluorite-Apatite

Luster:

Adamantine

Streak:

white

Optical Properties of Cafetite

Gladstone-Dale:

CI meas= -0.01 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.055 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.3333,KPDmeas= 0.3191,KC= 0.316

Optical Data:

Biaxial (-), a=1.95, b=2.08, g=2.11, bire=0.1600, 2V(Calc)=48, 2V(Meas)=38.

Calculated Properties of Cafetite

Electron Density:

r_electron=3.20 gm/cc
note: r_Cafetite=3.28 gm/cc.

Fermion Index

Fermion Index = 0.04506
Boson Index = 0.95494

Photoelectric:

PE_Cafetite= 10.44 barns/electron
U=PE_Cafetite x r_electron= 33.44 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Cafetite is Not Radioactive

Cafetite Classification

Dana Class:

8.7.3.1 (8)Multiple Oxides with Nb, Ta, and Ti

(8.7)Dana Type

(8.7.3)Dana Group

8.7.3.1 Cafetite Ca(Fe,Al)2Ti4O12·4(H2O) P 2₁/n 2/m

Strunz Class:

IV/D.05-10 IV - Oxides

IV/D - Oxides with metal : oxygen = 1:2 (MO2 and related compounds)

IV/D.05 - Cafetite series

IV/D.05-10 Cafetite Ca(Fe,Al)2Ti4O12·4(H2O) P 2₁/n 2/m

Other Cafetite Information

References:

NAME( Dana8) PHYS. PROP.(AmMin, Vol 88, p 424) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

See Also:

Links to other databases for Cafetite :
1 -Am. Min. Crystal Structure Database 2 -Athena 3 - EUROmin Project 4 -Google Images 5 -Google Scholar 6 -Handbook of Mineralogy (UofA) 7 -MinDAT 8 -MinMax(Deutsch) 9 -MinMax(English) 10 -Mineralienatlas (Deutsch) 11 -QUT Mineral Atlas 12 -École des Mines de Paris

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

Cafetite

Ca(Fe,Al)2Ti4O12·4(H2O)
Dana No: 8.7.3.1 Strunz No: IV/D.05-10
Locality:

Notes: