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Natrolite (Photo) [abbr. Ntr ]

Year of discovery: 1803 (Hohentwiel, Germany), 1897 (Japan)

Locality list: 122 localities of natrolite

• Na₂Al₂Si₃O₁₀,2H₂O
• [Na⁺₂][Al₂Si₃O₁₀]^2-,2H₂O

• Class: Natrolite group < Zeolite family
• Class: Tecto-Aluminosilicate - Zeolitic water
• Soluble in: HCl (Gel residue)
• Fluorescence: UV excitation (Yellow-Orange)
• Electrical: Piezoelectric, Pyroelectric
• Formed on dehydration of Paranatrolite.
• Hydrate to Paranatrolite under high pressure. (Reversible)

• Na₂ => Ca: Scolecite, Cowlesite
• Na₂ => Ba: Edingtonite

• Na => NaCa: Mesolite

• 2H₂O => 3H₂O: Gonnardite, Paranatrolite

• Color: Colorless, White
• Streak: White
• Luster: Vitreous
• Diaphaneity: Transparent-Translucent

• Habit: Prismatic

• Cleavage: Perfect on {110} (2 planes), Parting on {010} (1 plane)
• Hardness: 5-5.5
• Density: 2.3

• System: Orthorhombic
• Group: mm2, Fdd2
• Lattice: a=18.3, b=18.6, c=6.6

Etymology: Natro (Soda) in Latin