Jun 13 2014
Barbosalite was named to honor Aluizio Licinio de Miranda Barbosa, who is a Professor of Geology at the School of Mines, Ouro Preto, Brazil.
It belongs to the Lazulite mineral group, and forms a dimorphous series with lipscombite.
Properties of Barbosalite
The following are the key properties of barbosalite:
- Cell Data
- Space Group : P21/c
- a = 7.25
- b = 7.46
- c = 7.49
- β = 120°15’
- Z = 2
- Crystal Data
- Monoclinic, pseudo tetragonal
- Point Group: 2/m
- As stout prismatic to pseudocubic crystals, may have mosaic texture, to 0.25mm; generally as microcrystalline to powdery coatings
- Twinning: Contact twins with (001) as composition surface
- X-ray Powder Pattern: 3.361 (10), 3.313 (8), 4.84 (6), 3.239 (6), 3.160 (6), 2.327 (4), 1.309 (4)
- Chemical Composition
| Elements |
Content 1 |
Content 2 |
| Fe2O3 |
40.92 |
40.79 |
| FeO |
18.38 |
18.35 |
| MnO |
0.30 |
- |
| P2O5 |
36.07 |
36.26 |
| H2O |
[4.33] |
4.60 |
| Total |
[100.00] |
[100.00] |
- Optical Properties
- Translucent to nearly opaque
- Color: dark blue, blue green
- Streak: dark blue
- Luster: vitreous to earthy
- Pleochroism: X = Y = dark blue-green Z = dark olive-green
- Optical Class: Biaxial (+)
- Dispersion: r > v; strong
- Absorption: Strong, X=Y>Z
- α = 1.76-1.78; β = 1.77-1.81; γ = 1.835-1.84
- 2V(meas) = 64°
- Estimated Properties
| Electron density |
Bulk density (electron density) = 3.49 g/cm3
note: Specific gravity of barbosalite = 3.60 g/cm3 |
| Photoelectric |
PEBarbosalite = 13.60 barns/electron
U = PEBarbosalite x ρ electron density = 47.54 barns/cm3 |
| Fermion index |
Fermion index = 0.0092694342
Boson index = 0.9907305 |
Radioactivity
|
Barbosalite is not radioactive
|
How to Identify Barbosalite
The color of barbosalite varies from dark blue to blue-green. It exhibits a hardness of 6, and a vitreous to earthy luster.
Global Distribution
Barbosalite is widely distributed in the following locations:-
- Brazil – from Minas Gerais at the Sapucaia pegmatite mine, near Governador Valadares; good crystals from the Criminoso pegmatite mine, near Sao Jose Safira, Agua Boa
- USA – from Palermo #1 mine, near North Groton, New Hampshire; Williams pegmatite from Bull Moose and Tip Top mines, near Custer, South Dakota
- Australia – from Wilsons quarry, Thackaringa district, 40km south-west of Broken Hill, New South Wales; Wiperaminga Hill West quarry, Boolcoomata, South Australia
- Rwanda - from Buranga pegmatite, near Gatumba
- Morocco – from Angarf-Sud pegmatite, Tazenakht Plain
- Portugal – from mangualde pegmatite, near Mesquitela
Occurrence of Barbosalite and Useful Mineral Association
Barbosalite occurs in complex granitic pegmatites, formed by oxidation and hydration of primary phosphates. It is associated with minerals such as tavorite, hureaulite, heterosite, vivanite, triphylite, rocherite, and rockbridgeite.
References