Pyrochlore
Mineral (Na,Ca)2Nb2O6(OH,F)
Also called Fluorcalciopyrochlore and Hydroxycalciopyrochlore
Take care.
- Radioactive: Keep it in a closed, labelled box away from where people sit or sleep, handle it briefly, wash your hands after, and never grind or cut it.
About it
Small brown to black octahedrons in carbonatites and nepheline syenites, the main ore of niobium. Often a little radioactive from uranium and thorium; Oka, Quebec, and Araxá, Brazil, are known sources.
- Type
- Mineral
- Group
- Oxide, pyrochlore group
- Formula
- (Na,Ca)2Nb2O6(OH,F)
- Hardness (Mohs)
- 5–5.5
- Specific gravity
- 4.2–6.4
- Streak
- yellowish brown
- Lustre
- resinous, greasy, vitreous (glassy)
- Crystal system
- Isometric (cubic)
- Colours
- brown, reddish brown, yellow, black
- Transparency
- translucent, opaque
- Cleavage and fracture
- indistinct octahedral; subconchoidal to uneven fracture
Typical values: real specimens vary. For more, see mindat.org.