Allanite-(Ce)
Mineral CaCe(Al2Fe)(SiO4)(Si2O7)O(OH)
Also called Allanite and Orthite
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
Pitch-black tablets and grains in granite and pegmatite, often metamict and weakly radioactive from thorium; widespread in Ontario's Grenville rocks, Norway, and Madagascar.
- Type
- Mineral
- Group
- Silicate (sorosilicate), epidote group
- Formula
- CaCe(Al2Fe)(SiO4)(Si2O7)O(OH)
- Hardness (Mohs)
- 5.5–6
- Specific gravity
- 3.3–4.2
- Streak
- greyish brown
- Lustre
- vitreous (glassy), greasy
- Crystal system
- Monoclinic
- Colours
- black, brown, reddish brown
- Transparency
- transparent, translucent, opaque
- Cleavage and fracture
- poor; conchoidal to uneven fracture
Typical values: real specimens vary. For more, see mindat.org.