| Initial mineral | Alteration product | Converting temperature (˚C) |
| Maghemite | Hematite | 350 - 450 |
| Pyrrhotite | Magnetite | >500 |
| Pyrite | Magnetite | 350 - 500 |
| Lepidocrocite | Maghemite | 220 - 270 |
| Goethite | Hematite | 200 - 400 |
| Siderite | Magnetite | >200 |