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Laumontite (Photo) [abbr. Lmt ]

Year of discovery: 1805 (Huelgoat (Locmaria-Berrien), France), 1903 (Japan)

Locality list: 416 localities of laumontite

• CaAl₂Si₄O₁₂,4H₂O
• [Ca²⁺][(AlSi₂O₆)₂]^2-,4H₂O

• Class: Analcime group < Zeolite family
• Class: Tecto-Aluminosilicate - Zeolitic water
• Variety: Leonhardite (-H₂O)
• Soluble in: HCl (Gel residue)
• Fluorescence: UV excitation (White)
• Dehydrate to white powder.

• 4H₂O => 2H₂O: Wairakite

• Color: Colorless, Pale red
• Tarnish: White (by dehydration in the air)
• Streak: White
• Luster: Vitreous
• Diaphaneity: Transparent-Translucent

• Habit: Truncated prismatic

• Cleavage: Perfect on {010} and {110} (3 planes)
• Hardness: 3.5-4
• Density: 2.3

• System: Monoclinic
• Group: 2/m, C2/m
• Lattice: a=14.7, b=13.1, c=7.6, β=112.0

Etymology: F.P.N.G.Laumont, French mineralogist