Fergusonite-(Y)
Mineral YNbO4
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
Brown to black square prisms and bipyramids with a greasy to glassy shine in granite pegmatites. Usually radioactive from uranium and thorium; found in Norway, Madagascar, and Llano County, Texas.
- Type
- Mineral
- Group
- Oxide, fergusonite group
- Formula
- YNbO4
- Hardness (Mohs)
- 5.5–6.5
- Specific gravity
- 4.3–5.8
- Streak
- brown
- Lustre
- submetallic, vitreous (glassy), resinous
- Crystal system
- Tetragonal
- Colours
- brownish black, black, brown, yellow
- Transparency
- opaque, translucent
- Cleavage and fracture
- indistinct; subconchoidal fracture
Typical values: real specimens vary. For more, see mindat.org.