Foitite

Foitite is named after Franklin F.Foit, Jr., Washington State University, Pullman, in recognition of his on tourmaline-group minerals.

Foitite is a vacancy-dominant member of the Tourmaline Group. It forms translucent to opaque prismatic crystals with vitreous lustre. The colour is dark indigo with purple tints to bluish-black.
General Information
Chemical Formula
Na
 
x
[Fe
2+
2
(Al,Fe
3+
 
)]Al
 
6
(BO
 
3
)
 
3
Si
 
6
O
 
18
(OH)
 
4
Anthony et al, Handbook of mineralogy (2001)
Photos of natural/un-cut material from mindat.org
Physical Properties of Foitite
Mohs Hardness7 to 0
Anthony et al, Handbook of mineralogy (2001)
Specific Gravity3.17
Anthony et al, Handbook of mineralogy (2001)
TenacityBrittle
Anthony et al, Handbook of mineralogy (2001)
FractureIrregular
Anthony et al, Handbook of mineralogy (2001)
Optical Properties of Foitite
Optical CharacterUniaxial/-
Anthony et al, Handbook of mineralogy (2001)
PleochroismStrong: pale lavender - dark blue
Anthony et al, Handbook of mineralogy (2001)
Colour
Colour (General)Bluish black
Anthony et al, Handbook of mineralogy (2001)
TransparencyTranslucent
Anthony et al, Handbook of mineralogy (2001) Translucent in thin fragments
LustreVitreous
Anthony et al, Handbook of mineralogy (2001)
Crystallography of Foitite
Crystal SystemHexagonal
Anthony et al, Handbook of mineralogy (2001)
HabitCrystals prismatic, elongated and striated, with triangular cross section, to 5.5 cm
Anthony et al, Handbook of mineralogy (2001)
Geological Environment
Where found:Probably in granite pegmatites.
Anthony et al, Handbook of mineralogy (2001)
Further Information
Mineral information:Foitite information at mindat.org
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