May 12 2014
Brassite is a rare arsenate mineral, first discovered in 1973 in Jachymov (Joachimsthal), Czech Republic. The mineral was named after Rejane Brasse, who first synthesized the compound.
Properties of Brassite
The following are the key properties of Brassite:
- Cell Data
- Space Group: Pbca (synthetic)
- a = 7.472(1)
- b = 10.891(1)
- c = 16.585(5)
- Z = 8
- Crystal Data
- Orthorhombic
- Point Group: 2/m 2/m 2/m
- Cryptocrystalline crusts and powder, intermixed with other arsenates
- X-ray Powder Pattern: 4.97 (10), 3.20 (8), 3.07 (7), 4.14 (6), 3.88 (5), 2.324 (5), 4.54 (4)
- Chemical Composition
| Elements |
Content 1 |
Content 2 |
| As2O5 |
48.1 |
48.63 |
| H2O |
35.4 |
34.31 |
| MgO |
15.6 |
17.06 |
| CaO |
0.9 |
- |
| Total |
100 |
100 |
- Optical Properties
- Optical Class: Biaxial (+) (synthetic)
- Orientation: X = b; Y = a; Z = c
- α = 1.531(2)
- β = 1.546(2)
- γ = 1.562(2)
- 2V(meas.) = n.d.
- 2V(calc.) = 80°
- Estimated Properties
| Electron density |
Bulk density (electron density)=2.33 g/cm3
note: Specific gravity of Brassite =2.33 g/cm3 |
| Photoelectric |
PEBrassite = 20.91 barns/electron
U= PEBrassite x ρ Electron density= 48.66 barns/cm3 |
| Fermion index |
Fermion index = 0.01
Boson index = 0.99 |
Radioactivity
|
Brassite is not radioactive
|
How to Identify Brassite
Brassite is a white mineral, having white streak and perfect cleavage. The density of brassite is 2.28 g/cm3.
Global Distribution
Brassite is distributed in the following places:
- Jachymov (Joachimsthal), Czech Republic
- Bieber and Richelsdorf, Hesse, and Wittichen, Black Forest, Germany
- Ruben mine, Kohlendorf, Nowa Ruda (Neurode), Silesia, Poland
- Salsigne mine, 15km north of Carcassone, Aude, France
Occurrence of Brassite and Useful Mineral Association
Brassite occurs as a rare reaction product of arsenic-rich solutions with Ca–Mg carbonates. It is closely associated with dolomite, realgar, arsenic, rauenthalite, haidingerite, weilite, picropharmacolite, and pharmacolite.
References