| Other names: | Clay ironstone (when mixed with limonite and clay) |
| Mineral class: | Carbonate |
| Composition: | Iron carbonate, FeCO3 |
| Hardness: | 3.5 - 4 |
| Color: | Brown |
| Cleavage: | Perfect in 3 directions, not at right angles |
| Comments: | Scratched by knife but not penny. Fizzes in hot HCl. Weathers to limonite. Becomes magnetic after heating in candle flame. |