Editorial Feature

Bustamite - Occurrence, Properties, and Distribution

May 20 2014

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	PE_Bustamite = 10.09 barns/electron U=PE_Bustamite 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.