FORMATION CONDITIONS OF ANTHOPHYLLITE |
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| Abstract: | It has been learned from experimental studies of the system MgO-SiO2-H2O and of quaternary systems in the presence of Al2O3 that it is impossible to obtain anthophyllite as a stable phase below a pressure of 4, 000 atm. Regardless of how the problem of water is treated, the formation of anthophyllite is not affected by the lack of H2O because the reaction enstatite - quartz = anthophyllite takes place without either the absorption or release of water. The author assumes that this mineral is formed at higher pressures of about 6,000–8,000 atm and gives a corresponding diagram (figs. 1 and 2). The presence of Al2O3 appears to raise the pressure for the formation of anthophyllite still higher, while the presence of FeO appears to lower it.—Auth. English summ. |
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