Gedrite

Gedrite is named after its discovery locality, the Héas Valley, near Gédre, Hautes-Pyrénées, France.

Gedrite forms white, gray, brown, green, prismatic crystals or fibrous aggregates with vitreous lustre.
General Information
Chemical Formula
(Mg,Fe
2+
 
)
 
2
[(Mg,Fe
2+
 
)
 
3
Al
 
2
](Si
 
6
Al
 
2
)O
 
22
(OH)
 
2
Anthony et al, Handbook of mineralogy (2001)
Physical Properties of Gedrite
Mohs Hardness5.5 to 6
Anthony et al, Handbook of mineralogy (2001)
Specific Gravity3.15 to 3.259
Anthony et al, Handbook of mineralogy (2001)
TenacityBrittle
Anthony et al, Handbook of mineralogy (2001)
Cleavage QualityPerfect,Imperfect
Anthony et al, Handbook of mineralogy (2001)
Optical Properties of Gedrite
Refractive Index1.625 to 1.718
Anthony et al, Handbook of mineralogy (2001)
Optical CharacterBiaxial/+
Anthony et al, Handbook of mineralogy (2001)
PleochroismWeak to moderate, in browns, yellows, or gray.
Anthony et al, Handbook of mineralogy (2001)
Colour
Colour (General)White, gray, brown, green; colorless, gray, or brown in thin section.
Anthony et al, Handbook of mineralogy (2001)
TransparencyTransparent,Translucent
Anthony et al, Handbook of mineralogy (2001)
LustreVitreous
Anthony et al, Handbook of mineralogy (2001)
Crystallography of Gedrite
Crystal SystemOrthorhombic
Anthony et al, Handbook of mineralogy (2001)
HabitAs bladed and prismatic crystals; fibrous and semi-sheaflike aggregates.
Anthony et al, Handbook of mineralogy (2001)
Geological Environment
Where found:Widespread in medium- to high-grade metamorphic rocks; in metasomatized contact metamorphic rocks.
Anthony et al, Handbook of mineralogy (2001)
Further Information
Mineral information:Gedrite information at mindat.org
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