| Abstract: | Low temperature adiabatic calorimetry and high temperature differential scanning calorimetry have been used to measure the heat-capacity of ilmenite (FeTiO3) from 5 to 1000 K. These measurements yield S2980 = 108.9 J/(mol ?? K). Calculations from published experimental data on the reduction of ilmenite yield ??2980(I1) = -1153.9 kJ/(mol ?? K). These new data, combined with available experimental and thermodynamic data for other phases, have been used to calculate phase equilibria in the system Fe-Ti-O. Calculations for the subsystem Ti-O show that extremely low values of f{hook}O2 are necessary to stabilize TiO, the mineral hongquiite reported from the Tao district in China. This mineral may not be TiO, and it should be re-examined for substitution of other elements such as N or C. Consideration of solid-solution models for phases in the system Fe-Ti-O allows derivation of a new thermometer/oxybarometer for assemblages of ferropseudobrookite-pseudobrookitess and hematite-ilmenitess. Preliminary application of this new thermometer/oxybarometer to lunar and terrestrial lavas gives reasonable estimates of oxygen fugacities, but generally yields subsolidus temperatures, suggesting re-equilibration of one or more phases during cooling. ?? 1985. |
| Genre: | Article |
| ProdID: | 70012727 |
| Citation Author: | Anovitz, L. M.; Treiman, A. H.; Essene, E. J.; Hemingway, B. S.; Westrum, Jr. , E. F.; Wall, V. J.; Burriel, R.; Bohlen, S. R. |
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| Citation End Page: | 2040 |
| Citation Issue: | 10 |
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| Citation Language: | English |
| Citation Larger Work Title: | Geochimica et Cosmochimica Acta |
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| Citation Number Of Pages: | 14 |
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| Citation Search Results Text: | The heat-capacity of ilmenite and phase equilibria in the system Fe-T-O; 1985; Article; Journal; Geochimica et Cosmochimica Acta; Anovitz, L. M.; Treiman, A. H.; Essene, E. J.; Hemingway, B. S.; Westrum, Jr. , E. F.; Wall, V. J.; Burriel, R.; Bohlen, S. R. |
| Citation Start Page: | 2027 |
| Citation Volume: | 49 |
| Citation Year: | 1985 |
| Type: | citation/reference |
| Text: | The heat-capacity of ilmenite and phase equilibria in the system Fe-T-O; 1985; Article; Journal; Geochimica et Cosmochimica Acta; Anovitz, L. M.; Treiman, A. H.; Essene, E. J.; Hemingway, B. S.; Westrum, Jr. , E. F.; Wall, V. J.; Burriel, R.; Bohlen, S. R. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Tue, 1 Jan 1985 00:00 -0600 |
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