chondrodite
2Mg2SiO4·Mg(OH,F)2 (microprobe: Mg3.86Fe0.14(SiO4)·Mg0.00Ti0.05F1.38(OH)0.52O0.1, H assumed from stoichiometry)
third-order Birch-Murnaghan · Original · 1994
V₀
110.88
cm³/mol
Molar
K₀
136.200
GPa
Isothermal
K′
3.700
dimensionless
Volume (V₀)
| Value | Unit | Basis | Z |
|---|---|---|---|
| 110.88 | cm³/mol | Molar | — |
Reported value and unit are preserved as extracted. Z (formula units per cell) is not stored yet, so molar ↔ ų/f.u. conversion is not applied automatically.
Composition
| Oxide | Molar |
|---|---|
| MgO | 3.86 |
| FeO | 0.14 |
| TiO2 | 0.05 |
| SiO2 | 1 |
| H2O | 0.26 |
Formula: (O2H2F2)
Conditions & method
- Tref
- —
- Pref
- —
- Structure
- other / unspecified
- Method
- experiment (XRD / DAC / multianvil compression)static compression, x-ray diffraction in diamond anvil cell to 42.3 GPa, methanol:ethanol:water medium, ruby fluorescence pressure scale
- Sample
- natural chondrodite, U.C. Berkeley collection #13056 (same sample as Williams, 1992)
Source
- Paper
- Static compression of chondrodite: Implications for water in the upper mantle
- Authors
- J. W. Faust; Elise Knittle
- DOI
- 10.1029/94gl01592
- Year
- 1994
- Journal
- Geophysical Research Letters
- Origin
- Original (measured or fitted in the source paper)
Evidence from the paper
The lattice parameters of this sample at ambient pressure are ... giving a V0 of 110.88 (+0.01) cm3/mol ... we fit our compression data to a third-order Eulerian finite-strain equation of state (i.e. Birch-Murnaghan equation: Birch, 1978) ... we did not constrain the value of K0T'. Our results yield a K0T for chondrodite of 136.2 (±8.8) GPa, with K0T' equal to 3.7 (±0.4).
Additional notes
rho0
3.13 (+0.01) g/cm3 (also quoted as 3.127 g/cm3)
lattice parameters
a = 4.795 (±0.112) Å, b = 10.314 (±0.056) Å, c = 7.881 (±0.075) Å, α = 109.059°
max pressure
42.3 GPa
lower mantle relevance
Chondrodite breaks down to MgSiO3 perovskite, MgO and a hydrated melt at lower mantle pressures and temperatures; no EOS parameters reported for the perovskite or MgO breakdown products
note
Hydrous phase framed as upper-mantle water carrier; included because paper explicitly discusses lower-mantle P/T behavior with EOS numbers