Polycrase-(Y)
Mineral (Y,Ca,Ce,U,Th)(Ti,Nb,Ta)2O6
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
Black, flattened prisms in granite pegmatites, the titanium-rich partner of euxenite-(Y) and radioactive like it. Usually glassy inside from radiation damage; first described from southern Norway.
- Type
- Mineral
- Group
- Oxide, euxenite group
- Formula
- (Y,Ca,Ce,U,Th)(Ti,Nb,Ta)2O6
- Hardness (Mohs)
- 5–6
- Specific gravity
- 4.9–5.1
- Streak
- brown
- Lustre
- vitreous (glassy), resinous
- Crystal system
- Orthorhombic
- Colours
- black, brown
- Transparency
- opaque
- Cleavage and fracture
- none; conchoidal fracture
Typical values: real specimens vary. For more, see mindat.org.