Cafetite - Occurrence, Properties, and Distribution

Cafetite is a rare titanium oxide mineral first discovered in Afrikanda massif, Kola Peninsula, Russia. It was named for its composition Ca, Fe and Ti.

Properties of Cafetite

The following are the key properties of Cafetite:

  • Cell Data
    • Space Group: n.d
    • a = 31.34(5)
    • b = 12.12(3)
    • c = 4.96(1)
    • β = [90°]
    • Z = 16.
  • Crystal Data
    • Monoclinic, pseudo-orthorhombic.
    • Point Group: n.d.
    • Crystals columnar to acicular, elongated along [001], with striated prism faces; forms are {100}, {520}, {210}, several other minor.
    • In fibrous aggregates, radial to tangled masses.
    • X-ray Powder Pattern: 7.86 (10), 3.27 (8), 2.562 (8), 1.914 (7), 2.63 (4), 2.108 (4), 1.573 (4).
  • Chemical Composition
    Elements Content 1
    TiO2 54.11
    Fe2O3 22.00
    H2O+ 8.83
    CaO 6.23
    H2O- 3.46
    Al2O3 2.02
    MgO 1.44
    FeO 0.49
    K2O 0.40
    Na2O 0.28
    MnO 0.20
    Total 100.46
  • Optical Properties
    • Optical Class: Biaxial (–)
    • Orientation: Z ^ c = 2°–4°
    • Dispersion: Strong.
    • α = 1.95
    • β = 2.08
    • γ = 2.11
    • 2V(meas.) = 36.5°–39°.
  • Estimated Properties
    Electron density Bulk density (electron density) = 3.20 g/cm3
    note: Specific gravity of Cafetite = 3.28 g/cm3
    Photoelectric PECafetite = 10.44 barns/electron
    U = PECafetite x ρElectron density = 33.44 barns/cm3
    Fermion index Fermion index = 0.04
    Boson index = 0.96

    Radioactivity

    Cafetite is not radioactive.

How to Identify Cafetite

Cafetite can be identified as colorless or pale yellow crystals with good cleavage, white streaks and adamantine luster. It is transparent in nature. Its fractures appear brittle as shown by glasses and some of the non-metallic minerals. The mineral can be formed as needle-like crystals or aggregates. The relative hardness of cafetite ranges from 4 to 5, and its density is 3.28 g/cm3.

Global Distribution

Cafetite is mainly distributed in the Afrikanda pyroxenite massif, Kola Peninsula, Russia.

Occurrence of Cafetite and Useful Mineral Association

Cafetite occurs as a late mineral in miarolitic cavities in pegmatites cutting a pyroxenite massif. It is closely associated with kassite, clinochlore, phlogopite, baddeleyite, perovskite, anatase, titanite, titanomagnetite and ilmenite.

References

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