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Ferro-gedrite (Photo) [abbr. Fgd ]
Year of discovery: 1978 (World), 1957 (Japan)
Locality list: 3 localities of ferro-gedrite
- Fe5Al4Si6O22(OH)2
- [][Fe2+2][Fe2+3][Al3+2][(OH)2|(AlSi3O11)2]16-
- Color: Greenish gray, Brown, Bluish green
- Tarnish: Yellowish brown (Weathering)
- Streak: Gray
- Luster: Vitreous
- Diaphaneity: Transparent-Translucent
- Cleavage: Perfect on {110} (2 planes, 120 degree), Indistinct on {010} and {100} (2 planes)
- Hardness: 5.5-6
- Density: 3.6
- System: Orthorhombic
- Group: mmm, Pnma
- Lattice: a=18.5, b=17.9, c=5.3