majoritic garnet
Mg0.31Fe1.4Ca0.82K0.06Al0.67Si3.9O12 (synthesized from natural tholeiitic basalt)
third-order Birch-Murnaghan · Original · 1996
Why this differs from similar rows?
Fit to the static-compression data converging to K0=226.2 GPa with K' fixed to 4.0; paper notes an equally acceptable alternative fit (sibling row) fixing K0 to 180 GPa instead.
V₀
—
Unknown basis
K₀
226.200
GPa
Isothermal
K′
4
dimensionless
Volume (V₀)
| Value | Unit | Basis | Z |
|---|---|---|---|
| — | — | Unknown basis | — |
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 | 0.31 |
| FeO | 1.4 |
| CaO | 0.82 |
| K2O | 0.03 |
| Al2O3 | 0.335 |
| SiO2 | 3.9 |
Formula: Mg0.31Fe1.4Ca0.82K0.06Al0.67Si3.9O12
Conditions & method
- Tref
- 300 K
- Pref
- —
- Structure
- other / unspecified
- Method
- experiment (XRD / DAC / multianvil compression)static compression, x-ray diffraction in diamond-anvil cell (300 K)
- Sample
- basaltic garnet synthesized from natural tholeiite at ~20.8 GPa, laser-heated diamond cell
Source
- Paper
- The stability and equation of state of majoritic garnet synthesized from natura…
- Authors
- J. W. Faust; Elise Knittle
- DOI
- 10.1029/96gl03027
- Year
- 1996
- Journal
- Geophysical Research Letters
- Origin
- Original (measured or fitted in the source paper)
Evidence from the paper
We determined the isothermal bulk modulus (K0T) and pressure derivative (dK0T/dP or K0') using the standard normalized pressure (F) versus strain (f) method, with a third-order Birch-Murnaghan equation of state [Birch, 1978]. A weighted fit yields a K0T of 226.2 (±9.3) GPa when K0' is constrained to equal 4.0.
Additional notes
a0
11.491(±0.011) Å (zero pressure lattice parameter)
rho0
3.83 (±0.02) g/cm^3
lower mantle relevance
majoritic garnet phase formed from natural basalts is stable to about 42 (±3) GPa, ~1250 km depth