Hardness: 3.5 - 4
Habit: Aggregate of crystals or grains
Colours: Tan brown (typical)
| ||Crystal System: Hexagonal|
Cleavage: Perfect rhombohedral
Reaction with HCl: Weak
Identification in hand sample:
Identified by colour and hardness.
Produced by hydrothermal alteration of limestone. May also occur as concretionary or oolitic forms in clay ironstones.
Industrial / ecomonic uses:
Sometimes used as an iron ore. Also used in pigments where a red or brown colour is desirable.