Abstract
Hydrothermal experiments were carried out at 2 kbar, 600-860°C to resolve discrepancies among previous studies on fO2-T stability relations for the following equilibria: 1) andradite (And) = hematite (Hm) + wollastonite (Wo), 2) And = magnetite (Mt) + Wo + O2, 3) And + quartz (Qz) = hedenbergite (Hd) + Wo + O2, and 4) And + Mt + Qz = Hd + O2. A variety of O buffer and H2 generation techniques were used to access a wide range of fO2-T conditions. The results yielded an internally consistent set of experiments on andradite and hedenbergite stability. The ΔfG0 m,298 for andradite and hedenbergite calculated from the data are -5428.0 ± 5.9 and =2676.6 ± 5.3 kJ/mol, respectively. -from Authors
Original language | English |
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Pages (from-to) | 1327-1341 |
Number of pages | 15 |
Journal | American Mineralogist |
Volume | 75 |
Issue number | 11-12 |
State | Published - 1990 |
ASJC Scopus subject areas
- Geophysics
- Geochemistry and Petrology