Cooling history of orthopyroxenes.
Order-disorder transitions between ferrous iron and magnesium in orthopyroxenes [minerals close to the composition (Fe, Mg) SiO(3)] occur rapidly between approximately 480 degrees and 1000 degrees C. Disordering and ordering have been studied experimentally. The determination of the metastable ferrous iron site occupancy in orthopyroxenes from rapidly cooled volcanic rocks provides information on the cooling rates, especially from 600 degrees to 480 degrees C.
Hafner
S S
SS
Virgo
D
D