Thermal transformation of penwithite
Thermal transformation of penwithite in air has been studied minutely in the temperature range up to 1200°C, using the differential thermal, thermogravimetric, chemical, and X-ray analyses. A correlation of thermal and chemical data with phase determinations shows that the chemical reactions caused...
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| Published in | Ganseki kōbutsu kōshō gakkaishi Vol. 46; no. 1; pp. 17 - 25 |
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| Main Author | |
| Format | Journal Article |
| Language | English |
| Published |
Japan Association of Mineralogical Sciences
1961
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| Online Access | Get full text |
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| Summary: | Thermal transformation of penwithite in air has been studied minutely in the temperature range up to 1200°C, using the differential thermal, thermogravimetric, chemical, and X-ray analyses. A correlation of thermal and chemical data with phase determinations shows that the chemical reactions caused thermally are dehydration, oxidation of a part of Mn2+ to Mn4+, and reduction of Mn4+ formed at the former stage to Mn2+, in order of increasing temperature, and penwithite transforms, in general, into braunite at the low-temperature oxidation stage and into rhodonite at the high-temperature reduction stage. The braunite formed at the low-temperature oxidation stage contains a greater amount of SiO2 in its structure than naturally occuring braunite. At the high-temperature reduction stage, Fe3+, if it is present remarkably, combines with manganese oxides and forms jacobsite, and then excess SiO2 is released as silica minerals. |
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| ISSN: | 0021-4825 1883-0765 |
| DOI: | 10.2465/ganko1941.46.17 |