Fluor-buergerite
Mineral NaFe3Al6(Si6O18)(BO3)3O3F
Also called Buergerite
About it
Dark brown iron tourmaline with a bronze-gold sheen, from cavities in rhyolite near Mexquitic, San Luis Potosí, Mexico, its only notable locality.
- Type
- Mineral
- Group
- Silicate (cyclosilicate), tourmaline group
- Formula
- NaFe3Al6(Si6O18)(BO3)3O3F
- Hardness (Mohs)
- 7
- Specific gravity
- 3.31
- Streak
- yellow-brown
- Lustre
- vitreous (glassy)
- Crystal system
- Trigonal
- Colours
- dark brown, nearly black, with bronze sheen
- Transparency
- translucent, opaque
- Cleavage and fracture
- distinct prismatic
Typical values: real specimens vary. For more, see mindat.org.