Editorial Feature

Bustamite - Occurrence, Properties, and Distribution

Bustamite was named after General Anastasio Bustamente (1780-1853), of Mexico.

Properties of Bustamite

The following are the key properties of bustamite:

  • Cell Data
    • Space group: P1
    • a = 15.412
    • b = 7.157
    • c = 13.824
    • α = 89°29’
    • β = 94°51’
    • γ = 102°56’
    • Z = 12

  • Crystal Data
    • Triclinic
    • Point group: 1
    • Crystals prismatic, needlelike, to 2.5cm, or tabular on {001}
    • Commonly fibrous, cleavable massive
    • Twinning: Composition plane {110}, simple twins, uncommon
    • X-ray powder pattern: 2.880 (100), 2.989 (60), 3.19 (50), 1.776 (50), 2.227 (40), 1.665 (40), 2.711 (30)

  • Chemical Composition
    Elements Content 1 Content 2
    SiO2 48.44 48.31
    MnO 25.20 33.04
    CaO 25.20 14.93
    MgO 0.65 1.90
    ZnO 0.53 -
    LOI 0.34 -
    FeO 0.27 1.87
    Total 100.63 100.05

  • Optical Properties
    • Optical class: Biaxial (-)
    • Pleochroism: X = Z = orange; Y = rose
    • Orientation: X ^ a ≃ 15°; Y ^ b ≃ 35°; Z ^ c ≃ 30° - 35°
    • Dispersion: r < v, weak, strong crossed dispersion
    • α = 1.640-1.695; β = 1.651-1.708; γ = 1.653-1.710
    • 2V(meas.) = 34°- 60°

  • Estimated Properties
    Electron density Bulk density (electron density) = 3.27 g/cm3
    note: Specific gravity of bustamite = 3.38 g/cm3
    Photoelectric PEBustamite = 10.09 barns/electron
    U=PEBustamite x ρ electron density = 33.04 barns/cm3
    Fermion index Fermion index = 0.01
    Boson index = 0.99
    Radioactivity
    Bustamite is not radioactive

How to Identify Bustamite

Bustamite can be identified in the field by its color variations, such as brown-red, light pink, and pink. Its transparent to translucent form has {100} perfect, {110} good and {110} good cleavage. This mineral has a vitreous luster, with white streak.

The density of bustamite is 3.32 - 3.43 g/cm3 with a hardness of 5.5 to 6.5 - between a knife blade and pyrite.

Global Distribution

Bustamite is distributed in the following places:

  • Mexico - From Tetela de Ocampo, Hidalgo
  • USA - At Franklin, Sussex Co. New Jersey
  • Sweden - At Langban and in the Harstigen mine, near Persberg, Varmland
  • England - At the Treburland mine, Altarnun, Cornwall, and in the Railroad quarry, Meldon, near Okehampton, Devon
  • Scotland - At Camas Malag, Isle of Skye
  • Romania - From Baita (Rezbanya)
  • Italy - At Campiglia, Tuscany, and Schio, Vicenza
  • South Africa - From the N'Chwaning mine, near Kuruman, Cape Province
  • Australia - At Broken Hill, New South Wales
  • Japan - From the Obori mine, Yamagata Prefecture; the Noda-Tamagawa mine, Iwate Prefecture; the Kanoiri mine, Tochigi Prefecture; the Mikumo mine, Shiga Prefecture; and the Hijikuzu mine, Iwate Prefecture.

Occurrence of Bustamite and Useful Mineral Association

Bustamite occurs in manganese ores, formed by the metamorphism of manganese-bearing sediments with attendant metasomatism; it is typically associated with skarns.

It is often associated with minerals such as rhodonite, tephroite, glaucochroite, johannsenite, wollastonite, diopside, grossular, and calcite.

References

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