[ Top ] [ Japanese ]

Dravite (Photo) [abbr. Drv ]

Year of discovery: 1883 (Dobrova, Slovenia), 1939 (Japan)

Locality list: 80 localities of dravite

• NaMg₃Al₆(BO₃)₃Si₆O₁₈(OH)₄
• [Na⁺][Mg²⁺₃][Al³⁺₆][(OH)₃|OH|(BO₃)₃|(SiO₃)₆]^25-

• Class: Alkali-subgroup 1 < Alkali-tourmaline group < Tourmaline supergroup
• Class: Cyclosilicate (Single ring) - Borate - Hydroxide
• Fluorescence: Short UV excitation (Yellow-Orange)
• Electrical: Piezoelectric, Pyroelectric

• NaMg => []Al: Magnesiofoitite

• Mg => Fe: Schorl (Series)
• Mg => Mn: Tsilaisite

• Mg₂ => LiAl: Elbaite (Series)

• Al => Cr: Chromium-dravite

• OH => F: Fluor-dravite

• Mg(OH) => AlO: Oxy-dravite

• NaMg₃ => LiAl₂: Rossmanite

• Color: Brown
• Streak: Pale brown
• Luster: Vitreous
• Diaphaneity: Transparent-Translucent

• Habit: Long prismatic
• Striation: Parallel to elongation

• Cleavage: Poor on {1120} and {1011} (6 planes)
• Hardness: 7-7.5
• Density: 3.1

• System: Trigonal
• Group: 3m, R3m
• Lattice: a=16.0, c=7.2

Etymology: Drava river, Austria