Mineralpedia Details for Tetraferriannite
Tetraferriannite
- Formula
- KFe2+3(Si3Fe3+)O10(OH)2
- Crystal System
- Monoclinic
- Crystal Habit
- Scaly, Massive - Lamellar
- Cleavage
- Perfect, None, None
- Luster
- Vitreous - Adamantine
- Color
- brown, brownish black
- Streak
- light brown
- Class
- Monoclinic - Prismatic
- Hardness
- 2.5-3
- WebMineral
- View Tetraferriannite
- Mindat
- View Tetraferriannite
Tetraferriannite from Silver Crater mine, Bancroft, Ontario, Canada
Large black crystal 5.5cm across. Tetraferriannite is the ferric iron analogue Annite.
Click thumbnail images for larger view.
