May 28 2014
Rittmannite is a member of the Whiteite group. It was first discovered in 1989 from Mangualde pegmatite, near Mesquitela, and the Bendada pegmatite, near Guarda, Portugal. It was named after the Swiss volcanologist Alfred Rittmann, who is considered as the founder of European volcanology.
Properties of Rittmannite
The following are the key properties of Rittmannite:
- Cell Data
- Space Group: [P2/a] (by analogy to the whiteite group)
- a = 15.01(4)
- b = 6.89(3)
- c = 10.16(3)
- β = 112.82(25)°
- Z = 2
- Crystal Data
- Monoclinic
- Point Group: 2/m
- As crystals, flattened on {001}, pseudohexagonal, to 1mm, in subparallel aggregates
- X-ray Powder Pattern: 9.38 (s), 2.802 (s), 4.69 (ms), 5.66 (m), 4.93 (m), 4.85 (m), 3.530 (m)
- Chemical Composition
| Elements |
Content 1 |
| P2O5 |
35.9 |
| H2O |
[19.7] |
| MnO |
18.9 |
| Al2O3 |
11.3 |
| FeO |
10.4 |
| CaO |
3.3 |
| Fe2O3 |
2.6 |
| MgO |
1.5 |
| Total |
[103.6] |
- Optical Properties
- Optical Class: Biaxial (+)
- Orientation: X = b; Z ^ c = 7°
- α = 1.622
- β = [1.626]
- γ = [1.654]
- 2V(meas.) = 43(2)°
- Estimated Properties
| Electron density |
Bulk density (electron density) = 2.80 g/cm3
note: Specific gravity of Rittmannite = 2.81 g/cm3 |
| Photoelectric |
PERittmannite = 6.63 barns/electron
U = PERittmannite x ρElectron density = 18.58 barns/cm3 |
| Fermion index |
Fermion index = 0.001
Boson index = 0.998 |
Radioactivity
|
Rittmannite is not radioactive
|
How to Identify Rittmannite
Rittmannite has a light yellow color with white streak. It has indistinct cleavage, vitreous luster, and transparent nature.
The density of rittmannite is 2.81 g/cm3, and its relative hardness is 3.5.
Global Distribution
Rittmannite is distributed in the following places:
- Mangualde pegmatite, near Mesquitela
- Bendada pegmatite, near Guarda, Portugal
Occurrence of Rittmannite and Useful Mineral Association
Rittmannite occurs as a very rare mineral in phosphatic nodules in zoned granite pegmatite veins (Mangualde pegmatite, Portugal).
The minerals that are closely related to rittmannite are orthoclase, hureaulite, frondelite, and kryzhanovskite.
References