| Other names: | Yellow ochre, bog iron ore |
| Mineral class: | Oxide, Hydroxide |
| Composition: | Hydrated iron oxide or hydroxide. FeO(OH) nH2O + Fe2O3 nH2O |
| Hardness: | Variable (1 - 5) |
| Luster: | Earthy, glassy |
| Color: | Dark yellow-brown to black |
| Streak: | Yellow-brown |
| Crystal form: | Earthy masses. None apparent. |
| Environment: | Concretions and impurities in sedimentary formations |
| Uses: | Occasional use as an iron ore |
| Comments: | Will often mark paper; may be scratched by knife. Formed from weathering or alteration of iron-containing minerals. May give yellow cast to limestones and shales.
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