Jun 2 2014
Tancoite was first discovered in the Tanco Mine (pegmatite), Bernic Lake in Manitoba, Canada. It was named after its discovery locality.
Properties of Tancoite
The following are the key properties of Tancoite:
- Cell Data
- Space Group: Pbcb
- a = 6.948(2)
- b = 14.089(4)
- c = 14.065(3)
- Z = 8
- Crystal Data
- Orthorhombic
- Point Group: 2/m 2/m 2/m
- Crystals, typically equant to tabular {010}, elongated along [001], with {001}, {010} {100}, {021}, {111}, to 1mm, and in subparallel [001] druses
- X-ray Powder Pattern: 4.672 (100), 3.150 (100), 3.413 (90), 2.479 (90), 1.760 (40), 1.438 (40), 1.429 (40)
- Chemical Composition
| Elements |
Content 1 |
Content 2 |
| P2O5 |
50.1 |
49.31 |
| Na2O |
20.0 |
21.53 |
| Al2O3 |
18.3 |
17.71 |
| H2O |
6.8 |
6.26 |
| Li2O |
5.2 |
5.19 |
| CaO |
0.5 |
- |
| Total |
100.9 |
100.00 |
- Optical Properties
- Optical Class: Biaxial (–)
- Orientation: X = c; Y = z; Z = a
- Dispersion: r < v, weak
- α = 1.541(2)
- β = 1.563(2)
- γ = 1.564(2)
- 2V(meas.) = 23(2)°
- 2V(calc.) = 24°
- Estimated Properties
| Electron density |
Bulk density (electron density) = 2.72 g/cm3
note: Specific gravity of Tancoite = 2.75 g/cm3 |
| Photoelectric |
PETancoite = 1.58 barns/electron
U = PETancoite x ρElectron density = 4.30 barns/cm3 |
| Fermion index |
Fermion index = 0.0020
Boson index = 0.9979 |
| Radioactivity |
Tancoite is not radioactive |
Global Distribution
Tancoite is widely distributed in the Tanco mine, Bernic Lake, Manitoba, Canada.
Occurrence of Tancoite and Useful Mineral Association
Tancoite occurs in the cavities in dump material from a complex granite pegmatite.
It is closely associated with quartz, calcite, barite, cookeite, spodumene, apatite, and lithiophosphate.
References