TY - JOUR
T1 - Volume behavior of hydrous minerals at high pressure and temperature
T2 - II. Compressibilities of lawsonite, zoisite, clinozoisite, and epidote
AU - Holland, T. J.B.
AU - Redfern, S. A.T.
AU - Pawley, A. R.
PY - 1996/1/1
Y1 - 1996/1/1
N2 - The pressure dependence of the lattice parameters of natural zoisite [Ca2Al3Si3O12(OH)], clinozoisite [Ca2Al3Si3O12(OH)], and epidote [Ca2Al2FeSi3O12(OH)] as well as synthetic lawsonite [CaAl2Si2O7(OH)2·H 2O] have been measured at ambient temperatures by energy-dispersive X-ray diffraction in a diamond-anvil cell. The experimental results for each phase may be summarized concisely in terms of the ambient-temperature isothermal bulk modulus K298 (using the Murnaghan equation of state and assuming K′ = 4): Lawsonite: K298 = 191 ± 5 GPa; zoisite: K298 = 279 ± 9 GPa; clinozoisite: A298 = 154 ± 6 GPa; epidote: K298 = 162 ± 4 GPa. These new measurements, together with the new thermal expansion data in the companion paper (Pawley et al. 1996), were used to calculate some phase equilibria for lawsonite dehydration to high pressures for comparison with experimental brackets. Important discrepancies between calculated and experimentally determined reactions become evident above 3 GPa.
AB - The pressure dependence of the lattice parameters of natural zoisite [Ca2Al3Si3O12(OH)], clinozoisite [Ca2Al3Si3O12(OH)], and epidote [Ca2Al2FeSi3O12(OH)] as well as synthetic lawsonite [CaAl2Si2O7(OH)2·H 2O] have been measured at ambient temperatures by energy-dispersive X-ray diffraction in a diamond-anvil cell. The experimental results for each phase may be summarized concisely in terms of the ambient-temperature isothermal bulk modulus K298 (using the Murnaghan equation of state and assuming K′ = 4): Lawsonite: K298 = 191 ± 5 GPa; zoisite: K298 = 279 ± 9 GPa; clinozoisite: A298 = 154 ± 6 GPa; epidote: K298 = 162 ± 4 GPa. These new measurements, together with the new thermal expansion data in the companion paper (Pawley et al. 1996), were used to calculate some phase equilibria for lawsonite dehydration to high pressures for comparison with experimental brackets. Important discrepancies between calculated and experimentally determined reactions become evident above 3 GPa.
UR - http://www.scopus.com/inward/record.url?scp=0029750644&partnerID=8YFLogxK
U2 - 10.2138/am-1996-3-408
DO - 10.2138/am-1996-3-408
M3 - Article
AN - SCOPUS:0029750644
SN - 0003-004X
VL - 81
SP - 341
EP - 348
JO - American Mineralogist
JF - American Mineralogist
IS - 3-4
ER -