Aug 29 2013
Cassidyite is a triclinic-pinacoidal mineral containing phosphorus, oxygen, nickel, magnesium, hydrogen and calcium. It is a member of the fairfieldite group. The mineral was first discovered in 1967 from the Wolf Creek meteorite. It was named in honor of Dr. William A. Cassidy, who mapped the Wolf Creek, Australia, crater in 1953.
Properties of Cassidyite
The following are the key properties of Cassidyite:
- Cell Data
- Space Group: P1 or P1
- a = 5.71
- b = 6.73
- c = 5.41
- α = 96°49.5'
- β = 107°21.5'
- γ = 104°34.9'
- Z = [1].
- Crystal Data
- Triclinic
- Point Group: 1 or 1
- Fibrous, as spherules and thin crusts
- X-ray Powder Pattern: 2.70 (100), 3.03 (95), 2.67 (79), 3.23 (65), 3.13 (48), 1.660 (46), 3.49 (38).
- Chemical Composition
| Elements |
Content 1 |
Content 2 |
| P2O5 |
39.2 |
40.83 |
| CaO |
32.3 |
32.26 |
| NiO |
6.4 – 16.2 |
- |
| MgO |
2.2 – 5.7 |
– |
| CoO |
0.4 |
- |
| H2O |
- |
10.37 |
| Total |
100 |
100 |
- Optical Properties
- Optical Class: Biaxial
- Orientation: Length-slow
- α = 1.64–1.65
- β = n.d
- γ = 1.67–1.68
- 2V(meas.) = n.d.
- Estimated Properties
| Electron density |
Bulk density (electron density) = 3.15 g/cm3
note: Specific gravity of Cassidyite = 3.15 g/cm3 |
| Photoelectric |
PECassidyite = 8.45 barns/electron
U = PECassidyite x ρElectron density = 26.59 barns/cm3 |
| Fermion index |
Fermion index = 0.0036
Boson index = 0.9963 |
|
Radioactivity
|
Cassidyite is not radioactive.
|
How to Identify Cassidyite
Cassidyite is a transparent greenish mineral having a vitreous luster. The density of cassidyite is 3.1 g/cm3, and its hardness is 3.5.
Global Distribution
Cassidyite is widely distributed in the Wolf Creek meteorite.
Occurrence of Cassidyite and Useful Mineral Association
Cassidyite occurs as an alteration product of a highly weathered iron-nickel meteorite. It is closely associated with lipscombite, apatite, nickel-rich serpentine, jarosite, nickelian maghemite, goethite and reevesite.
References